485BPOS

As filed with the Securities and Exchange Commission on October 11, 2019
File Nos. 333-76651, 811-09301

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	o
Post-Effective Amendment No. 128	x
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT	x
OF 1940
Amendment No. 131	x
(Check appropriate box or boxes)

TIAA-CREF Funds
(Exact Name of Registrant as Specified in Charter)

730 Third Avenue
New York, New York 10017-3206

(Address of Principal Executive Offices) (Zip Code)
Registrant’s Telephone Number, including Area Code: (800) 842-2733

Jeremy D. Franklin, Esq.
TIAA-CREF Funds
8500 Andrew Carnegie Blvd.
Charlotte, North Carolina 28262

(Name and Address of Agent for Service)

Copy to:
Christopher P. Harvey, Esq.
Adam T. Teufel, Esq.
Dechert LLP
One International Place, 40th Floor
100 Oliver Street
Boston, Massachusetts 02110

Approximate Date of Proposed Public Offering:

As soon as practicable after effectiveness of the Registration Statement.

It is proposed that this filing will become effective (check appropriate box):

x Immediately upon filing pursuant to paragraph (b)

o On (date) pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(1)

o 75 days after filing pursuant to paragraph (a)(2)

o On (date) pursuant to paragraph (a)(1)

o On (date) pursuant to paragraph (a)(2) of rule 485

If appropriate, check the following box:

o This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

Explanatory Note

This post-effective amendment on Form 485BPOS is being submitted for the sole purpose of furnishing, in Exhibit 101, XBRL Interactive Data for the related official 485BPOS filing which was submitted to the Commission on September 26, 2019.

No other changes have been made to this Form 485BPOS. This Form 485BPOS does not reflect events that may have occurred subsequent to the original filing date, and does not modify or update any related disclosures made in the related official Form 485BPOS.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, TIAA-CREF Funds certifies that it meets all the requirements for effectiveness of this Registration Statement under Rule 485(b) under the Securities Act of 1933 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of New York, and State of New York on the 11th day of October 2019.

TIAA-CREF FUNDS
By:	/s/ Bradley Finkle
Name:	Bradley Finkle
Title:	Principal Executive Officer and President

Pursuant to the requirements of the Securities Act, this registration statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Bradley Finkle	Principal Executive Officer and President	October 11, 2019
Bradley Finkle	(Principal Executive Officer)
/s/ E. Scott Wickerham	Principal Financial Officer,	October  11, 2019
E. Scott Wickerham	Principal Accounting Officer and Treasurer
	(Principal Financial and Accounting Officer)

SIGNATURE OF TRUSTEE	DATE	SIGNATURE OF TRUSTEE	DATE
*	October 11, 2019	*	October 11, 2019
Forrest Berkley		Howell E. Jackson
*	October 11, 2019	*	October 11, 2019
Joseph A. Boateng		Thomas J. Kenny
*	October 11, 2019	*	October 11, 2019
Janice C. Eberly		James M. Poterba
*	October 11, 2019	*	October 11, 2019
Nancy A. Eckl		Maceo K. Sloan
*	October 11, 2019	*	October 11, 2019
Michael A. Forrester		Laura T. Starks
/s/ Rachael M. Zufall	October  11, 2019
Rachael M. Zufall as attorney-in-fact

* Signed by Rachael M. Zufall pursuant to powers of attorney previously filed with the Securities and Exchange Commission.

EXHIBIT LIST

101.	INS XBRL Instance Document
101.	SCH XBRL Taxonomy Extension Schema
101.	DEF XBRL Taxonomy Extension Definition Linkbase
101.	LAB XBRL Taxonomy Extension Label Linkbase
101.	PRE XBRL Taxonomy Extension Presentation Linkbase

XML

TIAA-CREF Lifecycle Index 2010 Fund

TIAA-CREF Lifecycle Index 2010 Fund

Investment objective

The Lifecycle Index 2010 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2010 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2010 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.19%	0.19%	0.19%	0.19%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.06%	0.14%	0.06%	0.31%
Total annual Fund operating expenses		0.25%	0.33%	0.40%	0.50%
Waivers and expense reimbursements	[3],[4]	(0.15%)	(0.15%)	(0.15%)	(0.15%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2010 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	65	91	113	145
5 years	126	170	209	265
10 years	$ 303	$ 403	$ 491	$ 614

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 19% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2010 and who may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 40.00% of the Fund’s assets to equity Underlying Funds and 60.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2010 and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2040. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; and Inflation-Protected Assets: 10.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	41.75%	U.S. Equity	29.28%	ŸEquity Index Fund	29.28%
		International Equity	12.47%	ŸInternational Equity Index Fund	8.94%
				ŸEmerging Markets Equity Index Fund	3.53%
Fixed-Income	58.25%	Fixed-Income	39.34%	ŸBond Index Fund	39.34%
		Short-Term Fixed-Income	9.44%	ŸShort-Term Bond Index Fund	9.44%
		Inflation- Protected Assets	9.47%	ŸInflation-Linked Bond Fund	9.47%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2010 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.02%.

Best quarter: 7.77%, for the quarter ended September 30, 2010. Worst quarter: -6.63%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2010 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(3.15%)	3.67%		5.92%		Sep. 30, 2009
Institutional Class		(2.87%)	3.94%		6.20%		Sep. 30, 2009
Advisor Class		(2.98%)	3.81%	[1]	6.00%	[1]	Dec. 04, 2015
Premier Class		(3.10%)	3.77%		6.04%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(4.03%)	2.92%		5.24%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(1.65%)	2.60%		4.51%
S&P Target Date 2010 Index		(3.10%)	3.40%		5.50%	[2]
Lifecycle Index 2010 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(2.94%)	4.01%		6.33%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.102% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI EAFE + Emerging Markets Index; 9.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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Label

Element

Value

TIAA-CREF Lifecycle Index 2035 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2035 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2035 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

7.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2035 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 74.00% of the Fund’s assets to equity Underlying Funds and 26.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2035 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2065. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 51.80%; International Equity: 22.20%; Fixed-Income: 26.00%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	76.16%	U.S. Equity	53.41%	ŸEquity Index Fund	53.41%
		International Equity	22.75%	ŸInternational Equity Index Fund	16.31%
				ŸEmerging Markets Equity Index Fund	6.44%
Fixed-Income	23.84%	Fixed-Income	23.84%	ŸBond Index Fund	23.84%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI EAFE + Emerging Markets Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2035 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 14.20%.

Bar Chart Closing [Text Block]

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Best quarter: 11.89%, for the quarter ended September 30, 2010. Worst quarter: -14.45%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

14.20%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.89%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.45%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2035 Fund | S&P Target Date 2035 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.88%)

5 Years

rr_AverageAnnualReturnYear05

4.69%

Since Inception

rr_AverageAnnualReturnSinceInception

8.06%

^[1]

TIAA-CREF Lifecycle Index 2035 Fund | Lifecycle Index 2035 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.83%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.28%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

8.76%

^[1],[2]

TIAA-CREF Lifecycle Index 2035 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.19%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

52

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

98

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 234

1 Year

rr_AverageAnnualReturnYear01

(5.73%)

5 Years

rr_AverageAnnualReturnYear05

5.22%

Since Inception

rr_AverageAnnualReturnSinceInception

8.65%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2035 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.28%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 19

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

81

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

148

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 347

1 Year

rr_AverageAnnualReturnYear01

(5.77%)

5 Years

rr_AverageAnnualReturnYear05

5.10%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

8.45%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2035 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.34%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

182

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 422

1 Year

rr_AverageAnnualReturnYear01

(5.90%)

5 Years

rr_AverageAnnualReturnYear05

5.06%

Since Inception

rr_AverageAnnualReturnSinceInception

8.48%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2035 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.44%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

237

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 546

Annual Return 2010

rr_AnnualReturn2010

13.41%

Annual Return 2011

rr_AnnualReturn2011

(1.49%)

Annual Return 2012

rr_AnnualReturn2012

15.06%

Annual Return 2013

rr_AnnualReturn2013

23.22%

Annual Return 2014

rr_AnnualReturn2014

6.51%

Annual Return 2015

rr_AnnualReturn2015

(0.73%)

Annual Return 2016

rr_AnnualReturn2016

8.14%

Annual Return 2017

rr_AnnualReturn2017

18.43%

Annual Return 2018

rr_AnnualReturn2018

(5.92%)

1 Year

rr_AverageAnnualReturnYear01

(5.92%)

5 Years

rr_AverageAnnualReturnYear05

4.96%

Since Inception

rr_AverageAnnualReturnSinceInception

8.38%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2035 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.54%)

5 Years

rr_AverageAnnualReturnYear05

4.33%

Since Inception

rr_AverageAnnualReturnSinceInception

7.84%

TIAA-CREF Lifecycle Index 2035 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.20%)

5 Years

rr_AverageAnnualReturnYear05

3.74%

Since Inception

rr_AverageAnnualReturnSinceInception

6.71%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI EAFE + Emerging Markets Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.069% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.031% of average daily net assets for Institutional Class shares; (ii) 0.181% of average daily net assets for Advisor Class shares; (iii) 0.181% of average daily net assets for Premier Class shares; and (iv) 0.281% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

TIAA-CREF Lifecycle 2035 Fund

TIAA-CREF Lifecycle 2035 Fund

Investment objective

The Lifecycle 2035 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2035 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2035 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.48%	0.48%	0.48%	0.48%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.54%	0.62%	0.69%	0.79%
Waivers and expense reimbursements	[4],[5]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.43%	0.51%	0.58%	0.68%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2035 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 44	$ 52	$ 59	$ 69
3 years	140	166	188	220
5 years	269	313	352	407
10 years	$ 646	$ 743	$ 828	$ 947

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2035 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 72.00% of the Fund’s assets to equity Underlying Funds, 23.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2035 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2065. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 50.40%; International Equity: 21.60%; Fixed-Income: 23.00%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00% and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	74.44%	U.S. Equity	52.20%	ŸGrowth & Income Fund	10.93%
				ŸLarge-Cap Growth Fund	9.89%
				ŸLarge-Cap Value Fund	9.58%
				ŸQuant Large-Cap Growth Fund	8.63%
				ŸQuant Large-Cap Value Fund	8.39%
				ŸQuant Small-Cap Equity Fund	2.68%
				ŸQuant Small/Mid-Cap Equity Fund	2.10%
		International Equity	22.24%	ŸQuant International Equity Fund	5.81%
				ŸInternational Equity Fund	4.84%
				ŸInternational Opportunities Fund	4.82%
				ŸEmerging Markets Equity Fund	3.81%
				ŸQuant International Small-Cap Equity Fund	2.96%
Fixed-Income	20.93%	Fixed-Income	20.93%	ŸBond Fund	10.99%
				ŸBond Plus Fund	6.80%
				ŸEmerging Markets Debt Fund	1.25%
				ŸInternational Bond Fund	1.09%
				ŸHigh-Yield Fund	0.80%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2035 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 14.56%.

Best quarter: 17.55%, for the quarter ended June 30, 2009. Worst quarter: -16.14%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2035 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(8.22%)	4.42%		9.91%		Oct. 15, 2004
Institutional Class		(8.04%)	4.67%		10.17%		Jan. 17, 2007
Advisor Class		(7.98%)	4.56%	[1]	9.98%	[1]	Dec. 04, 2015
Premier Class		(8.12%)	4.53%		10.02%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(9.65%)	2.87%		8.68%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(4.01%)	3.19%		7.93%
S&P Target Date 2035 Index		(6.88%)	4.69%		9.38%
Lifecycle 2035 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(6.03%)	5.23%		10.17%

Current performance of the Fund’s shares may be higher or lower than that shown above.

 
After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2020 Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifecycle Index 2020 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle Index 2020 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.

Portfolio Turnover, Rate

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12.00%

Expenses Restated to Reflect Current [Text]

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Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2020 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 50.00% of the Fund’s assets to equity Underlying Funds and 50.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2020 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2050. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 35.00%; International Equity: 15.00%; Fixed-Income: 38.00%; Short-Term Fixed-Income: 6.00%; and Inflation-Protected Assets: 6.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	52.40%	U.S. Equity	36.75%	ŸEquity Index Fund	36.75%
		International Equity	15.65%	ŸInternational Equity Index Fund	11.22%
				ŸEmerging Markets Equity Index Fund	4.43%
Fixed-Income	47.60%	Fixed-Income	36.62%	ŸBond Index Fund	36.62%
		Short-Term Fixed-Income	5.48%	ŸShort-Term Bond Index Fund	5.48%
		Inflation- Protected Assets	5.50%	ŸInflation-Linked Bond Fund	5.50%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI EAFE + Emerging Markets Index; 5.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2020 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 11.35%.

Bar Chart Closing [Text Block]

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Best quarter: 9.39%, for the quarter ended September 30, 2010. Worst quarter: -9.69%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

11.35%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

9.39%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.69%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2020 Fund | S&P Target Date 2020 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.16%)

5 Years

rr_AverageAnnualReturnYear05

4.10%

Since Inception

rr_AverageAnnualReturnSinceInception

6.82%

^[1]

TIAA-CREF Lifecycle Index 2020 Fund | Lifecycle Index 2020 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.83%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.48%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

7.25%

^[1],[2]

TIAA-CREF Lifecycle Index 2020 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.21%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

56

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

107

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 257

1 Year

rr_AverageAnnualReturnYear01

(3.75%)

5 Years

rr_AverageAnnualReturnYear05

4.41%

Since Inception

rr_AverageAnnualReturnSinceInception

7.12%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2020 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.29%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

82

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

152

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 357

1 Year

rr_AverageAnnualReturnYear01

(3.86%)

5 Years

rr_AverageAnnualReturnYear05

4.27%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

6.92%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2020 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.36%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

105

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

191

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 445

1 Year

rr_AverageAnnualReturnYear01

(3.92%)

5 Years

rr_AverageAnnualReturnYear05

4.25%

Since Inception

rr_AverageAnnualReturnSinceInception

6.96%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2020 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.46%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

137

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

247

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 569

Annual Return 2010

rr_AnnualReturn2010

11.69%

Annual Return 2011

rr_AnnualReturn2011

1.32%

Annual Return 2012

rr_AnnualReturn2012

11.96%

Annual Return 2013

rr_AnnualReturn2013

15.27%

Annual Return 2014

rr_AnnualReturn2014

6.27%

Annual Return 2015

rr_AnnualReturn2015

(0.42%)

Annual Return 2016

rr_AnnualReturn2016

6.41%

Annual Return 2017

rr_AnnualReturn2017

13.37%

Annual Return 2018

rr_AnnualReturn2018

(3.97%)

1 Year

rr_AverageAnnualReturnYear01

(3.97%)

5 Years

rr_AverageAnnualReturnYear05

4.16%

Since Inception

rr_AverageAnnualReturnSinceInception

6.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2020 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.74%)

5 Years

rr_AverageAnnualReturnYear05

3.47%

Since Inception

rr_AverageAnnualReturnSinceInception

6.26%

TIAA-CREF Lifecycle Index 2020 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.11%)

5 Years

rr_AverageAnnualReturnYear05

3.03%

Since Inception

rr_AverageAnnualReturnSinceInception

5.35%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI EAFE + Emerging Markets Index; 5.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.089% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.011% of average daily net assets for Institutional Class shares; (ii) 0.161% of average daily net assets for Advisor Class shares; (iii) 0.161% of average daily net assets for Premier Class shares; and (iv) 0.261% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

Label

Element

Value

TIAA-CREF Lifestyle Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifestyle Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks current income with some capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

29.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking current income with some capital appreciation through a relatively stable asset allocation strategy targeting an income-oriented and conservative risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 20% of the Fund’s assets in equity Underlying Funds and (2) approximately 80% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	20.46%	U.S. Equity	15.33%	ŸLarge-Cap Growth Fund	3.63%
				ŸLarge-Cap Value Fund	3.52%
				ŸQuant Large-Cap Growth Fund	3.32%
				ŸGrowth & Income Fund	3.21%
				ŸQuant Small-Cap Equity Fund	0.72%
				ŸQuant Small/Mid-Cap Equity Fund	0.62%
				ŸQuant Large-Cap Value Fund	0.31%
		International Equity	5.13%	ŸInternational Equity Fund	1.59%
				ŸInternational Opportunities Fund	1.32%
				ŸEmerging Markets Equity Fund	1.05%
				ŸQuant International Small-Cap Equity Fund	0.82%
				ŸQuant International Equity Fund	0.35%
Fixed-Income	79.54%	Fixed-Income	38.85%	ŸBond Plus Fund	19.93%
				ŸBond Fund	18.92%
		Short-Term Fixed-Income	40.69%	ŸShort-Term Bond Fund	40.69%

Total 100.00% 100.00% 100.00%

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a higher percentage of fixed-income Underlying Funds, Fixed-Income Underlying Funds Risks are expected to predominate.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifestyle Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 40.0% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; 14.0% Russell 3000® Index; and 6.0% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Income Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 7.44%.

Bar Chart Closing [Text Block]

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Best quarter: 3.94%, for the quarter ended March 31, 2012. Worst quarter: -2.77%, for the quarter ended December 31, 2018.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

7.44%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.94%

Lowest Quarterly Return, Label

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Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.77%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifestyle Income Fund | Morningstar Conservative Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.20%)

5 Years

rr_AverageAnnualReturnYear05

2.54%

Since Inception

rr_AverageAnnualReturnSinceInception

3.31%

^[1]

TIAA-CREF Lifestyle Income Fund | Lifestyle Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

(0.87%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

2.66%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

3.38%

^[1],[2]

TIAA-CREF Lifestyle Income Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.32%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.68%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.42%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 43

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

191

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

353

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 822

Annual Return 2012

rr_AnnualReturn2012

8.53%

Annual Return 2013

rr_AnnualReturn2013

5.05%

Annual Return 2014

rr_AnnualReturn2014

3.54%

Annual Return 2015

rr_AnnualReturn2015

0.77%

Annual Return 2016

rr_AnnualReturn2016

4.22%

Annual Return 2017

rr_AnnualReturn2017

7.43%

Annual Return 2018

rr_AnnualReturn2018

(2.04%)

1 Year

rr_AverageAnnualReturnYear01

(2.04%)

5 Years

rr_AverageAnnualReturnYear05

2.74%

Since Inception

rr_AverageAnnualReturnSinceInception

3.87%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Income Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.22%)

5 Years

rr_AverageAnnualReturnYear05

1.58%

Since Inception

rr_AverageAnnualReturnSinceInception

2.74%

TIAA-CREF Lifestyle Income Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(0.97%)

5 Years

rr_AverageAnnualReturnYear05

1.69%

Since Inception

rr_AverageAnnualReturnSinceInception

2.60%

TIAA-CREF Lifestyle Income Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.33%

^[5]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.32%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.75%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.25%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

215

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

392

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 907

1 Year

rr_AverageAnnualReturnYear01

(2.04%)

5 Years

rr_AverageAnnualReturnYear05

2.72%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

3.86%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifestyle Income Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.32%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.83%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.57%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 58

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

239

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

435

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,001

1 Year

rr_AverageAnnualReturnYear01

(2.26%)

5 Years

rr_AverageAnnualReturnYear05

2.57%

Since Inception

rr_AverageAnnualReturnSinceInception

3.71%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Income Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.50%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.32%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.92%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.25%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.67%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 68

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

268

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

485

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,108

1 Year

rr_AverageAnnualReturnYear01

(2.27%)

5 Years

rr_AverageAnnualReturnYear05

2.48%

Since Inception

rr_AverageAnnualReturnSinceInception

3.61%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Income Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.28%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.32%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.95%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.25%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

278

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

501

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,144

1 Year

rr_AverageAnnualReturnYear01

(2.30%)

5 Years

rr_AverageAnnualReturnYear05

2.44%

Since Inception

rr_AverageAnnualReturnSinceInception

3.58%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

[1] Performance is calculated from the inception date of the Institutional Class.

[2] As of the close of business on December 31, 2018, the Lifestyle Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 40.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; 14.0% Russell 3000® Index; and 6.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[5] Restated to reflect estimate for the current fiscal year.

[6] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

XML

Label

Element

Value

TIAA-CREF Lifecycle Retirement Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Retirement Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Retirement Income Fund seeks high total return over time primarily through income,

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

with a secondary emphasis on capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 25% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

25.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy that will not gradually adjust over time and is designed for investors who are already in retirement (i.e., have already passed their retirement year) and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 35.00% of the Fund’s assets to equity Underlying Funds, 60.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations may be changed and actual allocations may vary up to ten percentage points from the targets. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020 which may change, are approximately as follows: U.S. Equity: 24.50%; International Equity: 10.50%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; Inflation-Protected Assets: 10.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change. Investors should note that the Fund has a significant level of equity exposure and this exposure could cause fluctuation in the value of the Fund depending on the performance of the equity markets generally.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. The Fund has relatively fixed asset allocations that will not gradually adjust over time. Underlying Fund allocations may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	36.02%	U.S. Equity	25.26%	ŸGrowth & Income Fund	5.30%
				ŸLarge-Cap Growth Fund	4.78%
				ŸLarge-Cap Value Fund	4.63%
				ŸQuant Large-Cap Growth Fund	4.18%
				ŸQuant Large-Cap Value Fund	4.06%
				ŸQuant Small-Cap Equity Fund	1.29%
				ŸQuant Small/Mid-Cap Equity Fund	1.02%
		International Equity	10.76%	ŸQuant International Equity Fund	2.81%
				ŸInternational Equity Fund	2.34%
				ŸInternational Opportunities Fund	2.34%
				ŸEmerging Markets Equity Fund	1.84%
				ŸQuant International Small-Cap Equity Fund	1.43%
Fixed-Income	59.35%	Fixed-Income	38.61%	ŸBond Fund	19.80%
				ŸBond Plus Fund	12.88%
				ŸEmerging Markets Debt Fund	2.13%
				ŸInternational Bond Fund	2.07%
				ŸHigh-Yield Fund	1.73%
		Short-Term Fixed-Income	10.85%	ŸShort-Term Bond Fund	10.85%
		Inflation- Protected Assets	9.89%	ŸInflation-Linked Bond Fund	9.89%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor, Premier and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI All Country World Index ex USA Investable Market Index; 10.0% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Retirement Income Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 9.91%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 8.88%, for the quarter ended September 30, 2009. Worst quarter: -6.10%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

9.91%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.88%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(6.10%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Retirement Income Fund | S&P Target Date Retirement Income Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.54%)

5 Years

rr_AverageAnnualReturnYear05

3.06%

10 Years

rr_AverageAnnualReturnYear10

5.31%

TIAA-CREF Lifecycle Retirement Income Fund | Lifecycle Retirement Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.94%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

3.71%

^[1]

10 Years

rr_AverageAnnualReturnYear10

6.55%

^[1]

TIAA-CREF Lifecycle Retirement Income Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.08%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.53%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.37%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 38

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

259

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 629

1 Year

rr_AverageAnnualReturnYear01

(3.84%)

5 Years

rr_AverageAnnualReturnYear05

3.67%

10 Years

rr_AverageAnnualReturnYear10

6.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle Retirement Income Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.16%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.61%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

158

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

303

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 726

1 Year

rr_AverageAnnualReturnYear01

(3.80%)

5 Years

rr_AverageAnnualReturnYear05

3.56%

^[7]

10 Years

rr_AverageAnnualReturnYear10

6.68%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Retirement Income Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.08%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.68%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.52%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 53

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

180

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

341

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 811

1 Year

rr_AverageAnnualReturnYear01

(3.90%)

5 Years

rr_AverageAnnualReturnYear05

3.52%

10 Years

rr_AverageAnnualReturnYear10

6.70%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Retirement Income Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.33%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.78%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.62%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 63

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

212

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

396

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 931

Annual Return 2009

rr_AnnualReturn2009

16.08%

Annual Return 2010

rr_AnnualReturn2010

10.44%

Annual Return 2011

rr_AnnualReturn2011

2.41%

Annual Return 2012

rr_AnnualReturn2012

11.27%

Annual Return 2013

rr_AnnualReturn2013

9.70%

Annual Return 2014

rr_AnnualReturn2014

4.18%

Annual Return 2015

rr_AnnualReturn2015

0.09%

Annual Return 2016

rr_AnnualReturn2016

5.69%

Annual Return 2017

rr_AnnualReturn2017

11.75%

Annual Return 2018

rr_AnnualReturn2018

(4.01%)

1 Year

rr_AverageAnnualReturnYear01

(4.01%)

5 Years

rr_AverageAnnualReturnYear05

3.41%

10 Years

rr_AverageAnnualReturnYear10

6.60%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle Retirement Income Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.55%)

5 Years

rr_AverageAnnualReturnYear05

2.07%

10 Years

rr_AverageAnnualReturnYear10

5.45%

TIAA-CREF Lifecycle Retirement Income Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.77%)

5 Years

rr_AverageAnnualReturnYear05

2.25%

10 Years

rr_AverageAnnualReturnYear10

4.93%

TIAA-CREF Lifecycle Retirement Income Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.81%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.19%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.62%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 63

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

218

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

410

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 964

1 Year

rr_AverageAnnualReturnYear01

(4.00%)

5 Years

rr_AverageAnnualReturnYear05

3.40%

10 Years

rr_AverageAnnualReturnYear10

6.63%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

[1] As of the close of business on December 31, 2018, the Lifecycle Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI All Country World Index ex USA Investable Market Index; 10.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; (iv) 0.25% of average daily net assets for Retirement Class shares; and (v) 0.25% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2020 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2020 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2020 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

23.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2020 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 45.00% of the Fund’s assets to equity Underlying Funds, 50.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2020 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2050. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 31.50%; International Equity: 13.50%; Fixed-Income: 38.00%; Short-Term Fixed-Income: 6.00%; Inflation-Protected Assets: 6.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	47.90%	U.S. Equity	33.60%	ŸGrowth & Income Fund	7.03%
				ŸLarge-Cap Growth Fund	6.38%
				ŸLarge-Cap Value Fund	6.17%
				ŸQuant Large-Cap Growth Fund	5.55%
				ŸQuant Large-Cap Value Fund	5.40%
				ŸQuant Small-Cap Equity Fund	1.72%
				ŸQuant Small/Mid-Cap Equity Fund	1.35%
		International Equity	14.30%	ŸQuant International Equity Fund	3.73%
				ŸInternational Equity Fund	3.11%
				ŸInternational Opportunities Fund	3.10%
				ŸEmerging Markets Equity Fund	2.45%
				ŸQuant International Small-Cap Equity Fund	1.91%
Fixed-Income	47.43%	Fixed-Income	35.46%	ŸBond Fund	18.15%
				ŸBond Plus Fund	11.86%
				ŸEmerging Markets Debt Fund	1.98%
				ŸInternational Bond Fund	1.90%
				ŸHigh-Yield Fund	1.57%
		Short-Term Fixed-Income	6.47%	ŸShort-Term Bond Fund	6.47%
		Inflation- Protected Assets	5.50%	ŸInflation-Linked Bond Fund	5.50%
Real Estate	4.67%	Direct Real Estate	4.67%	ŸTIAA-CREF Real Property Fund LP	4.67%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI All Country World Index ex USA Investable Market Index; 5.4% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2020 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 11.48%.

Bar Chart Closing [Text Block]

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Best quarter: 13.85%, for the quarter ended June 30, 2009. Worst quarter: -11.24%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

11.48%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.85%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(11.24%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2020 Fund | S&P Target Date 2020 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.16%)

5 Years

rr_AverageAnnualReturnYear05

4.10%

10 Years

rr_AverageAnnualReturnYear10

7.86%

TIAA-CREF Lifecycle 2020 Fund | Lifecycle 2020 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.97%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

4.41%

^[1]

10 Years

rr_AverageAnnualReturnYear10

8.37%

^[1]

TIAA-CREF Lifecycle 2020 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.44%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.51%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.39%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 40

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

130

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

252

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 608

1 Year

rr_AverageAnnualReturnYear01

(5.18%)

5 Years

rr_AverageAnnualReturnYear05

4.24%

10 Years

rr_AverageAnnualReturnYear10

8.66%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2020 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.44%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.59%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.47%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 48

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

155

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

296

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 706

1 Year

rr_AverageAnnualReturnYear01

(5.15%)

5 Years

rr_AverageAnnualReturnYear05

4.11%

^[7]

10 Years

rr_AverageAnnualReturnYear10

8.46%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2020 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.44%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.66%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.54%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 55

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

177

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

334

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 791

1 Year

rr_AverageAnnualReturnYear01

(5.26%)

5 Years

rr_AverageAnnualReturnYear05

4.08%

10 Years

rr_AverageAnnualReturnYear10

8.50%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2020 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.44%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.76%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.64%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 65

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

209

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

389

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 911

Annual Return 2009

rr_AnnualReturn2009

23.15%

Annual Return 2010

rr_AnnualReturn2010

13.15%

Annual Return 2011

rr_AnnualReturn2011

(0.52%)

Annual Return 2012

rr_AnnualReturn2012

14.28%

Annual Return 2013

rr_AnnualReturn2013

16.30%

Annual Return 2014

rr_AnnualReturn2014

4.52%

Annual Return 2015

rr_AnnualReturn2015

0.17%

Annual Return 2016

rr_AnnualReturn2016

6.45%

Annual Return 2017

rr_AnnualReturn2017

15.21%

Annual Return 2018

rr_AnnualReturn2018

(5.38%)

1 Year

rr_AverageAnnualReturnYear01

(5.38%)

5 Years

rr_AverageAnnualReturnYear05

3.97%

10 Years

rr_AverageAnnualReturnYear10

8.39%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2020 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.97%)

5 Years

rr_AverageAnnualReturnYear05

2.35%

10 Years

rr_AverageAnnualReturnYear10

7.07%

TIAA-CREF Lifecycle 2020 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.42%)

5 Years

rr_AverageAnnualReturnYear05

2.74%

10 Years

rr_AverageAnnualReturnYear10

6.53%

[1] As of the close of business on December 31, 2018, the Lifecycle 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI All Country World Index ex USA Investable Market Index; 5.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2050 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2050 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2050 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 5% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

5.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2050 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 91.25% of the Fund’s assets to equity Underlying Funds and 8.75% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2050 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2080. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.87%; International Equity: 27.38%; Fixed-Income: 8.75%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	91.65%	U.S. Equity	64.27%	ŸEquity Index Fund	64.27%
		International Equity	27.38%	ŸInternational Equity Index Fund	19.63%
				ŸEmerging Markets Equity Index Fund	7.75%
Fixed-Income	8.35%	Fixed-Income	8.35%	ŸBond Index Fund	8.35%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI EAFE + Emerging Markets Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2050 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.90%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 11.85%, for the quarter ended September 30, 2010. Worst quarter: -14.85%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.90%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.85%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.85%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2050 Fund | S&P Target Date 2050 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.94%)

5 Years

rr_AverageAnnualReturnYear05

5.01%

Since Inception

rr_AverageAnnualReturnSinceInception

8.64%

^[1]

TIAA-CREF Lifecycle Index 2050 Fund | Lifecycle Index 2050 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.14%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.65%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

9.14%

^[1],[2]

TIAA-CREF Lifecycle Index 2050 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.19%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

52

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

98

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 234

1 Year

rr_AverageAnnualReturnYear01

(7.01%)

5 Years

rr_AverageAnnualReturnYear05

5.59%

Since Inception

rr_AverageAnnualReturnSinceInception

9.03%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2050 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.13%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.28%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

80

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

147

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 346

1 Year

rr_AverageAnnualReturnYear01

(7.05%)

5 Years

rr_AverageAnnualReturnYear05

5.45%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

8.83%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2050 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.34%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

182

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 422

1 Year

rr_AverageAnnualReturnYear01

(7.13%)

5 Years

rr_AverageAnnualReturnYear05

5.43%

Since Inception

rr_AverageAnnualReturnSinceInception

8.87%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2050 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.44%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

237

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 546

Annual Return 2010

rr_AnnualReturn2010

13.51%

Annual Return 2011

rr_AnnualReturn2011

(1.70%)

Annual Return 2012

rr_AnnualReturn2012

15.39%

Annual Return 2013

rr_AnnualReturn2013

24.88%

Annual Return 2014

rr_AnnualReturn2014

6.53%

Annual Return 2015

rr_AnnualReturn2015

(0.91%)

Annual Return 2016

rr_AnnualReturn2016

9.23%

Annual Return 2017

rr_AnnualReturn2017

21.18%

Annual Return 2018

rr_AnnualReturn2018

(7.26%)

1 Year

rr_AverageAnnualReturnYear01

(7.26%)

5 Years

rr_AverageAnnualReturnYear05

5.32%

Since Inception

rr_AverageAnnualReturnSinceInception

8.76%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2050 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.80%)

5 Years

rr_AverageAnnualReturnYear05

4.72%

Since Inception

rr_AverageAnnualReturnSinceInception

8.23%

TIAA-CREF Lifecycle Index 2050 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.95%)

5 Years

rr_AverageAnnualReturnYear05

4.06%

Since Inception

rr_AverageAnnualReturnSinceInception

7.05%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI EAFE + Emerging Markets Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.061% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.039% of average daily net assets for Institutional Class shares; (ii) 0.189% of average daily net assets for Advisor Class shares; (iii) 0.189% of average daily net assets for Premier Class shares; and (iv) 0.289% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

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TIAA-CREF Lifecycle 2025 Fund

TIAA-CREF Lifecycle 2025 Fund

Investment objective

The Lifecycle 2025 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2025 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2025 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.45%	0.45%	0.45%	0.45%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.12%	0.04%	0.29%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.52%	0.60%	0.67%	0.77%
Waivers and expense reimbursements	[4],[5]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.41%	0.49%	0.56%	0.66%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2025 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 42	$ 50	$ 57	$ 67
3 years	134	159	182	213
5 years	258	302	341	396
10 years	$ 621	$ 719	$ 804	$ 924

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2025 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 54.00% of the Fund’s assets to equity Underlying Funds, 41.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2025 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2055. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 37.80%; International Equity: 16.20%; Fixed-Income: 33.00%; Short-Term Fixed-Income: 4.00%; Inflation-Protected Assets: 4.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	56.78%	U.S. Equity	39.82%	ŸGrowth & Income Fund	8.34%
				ŸLarge-Cap Growth Fund	7.56%
				ŸLarge-Cap Value Fund	7.30%
				ŸQuant Large-Cap Growth Fund	6.57%
				ŸQuant Large-Cap Value Fund	6.40%
				ŸQuant Small-Cap Equity Fund	2.05%
				ŸQuant Small/Mid-Cap Equity Fund	1.60%
		International Equity	16.96%	ŸQuant International Equity Fund	4.42%
				ŸInternational Equity Fund	3.69%
				ŸInternational Opportunities Fund	3.68%
				ŸEmerging Markets Equity Fund	2.91%
				ŸQuant International Small-Cap Equity Fund	2.26%
Fixed-Income	38.57%	Fixed-Income	30.54%	ŸBond Fund	15.57%
				ŸBond Plus Fund	10.25%
				ŸEmerging Markets Debt Fund	1.75%
				ŸInternational Bond Fund	1.65%
				ŸHigh-Yield Fund	1.32%
		Short-Term Fixed-Income	4.51%	ŸShort-Term Bond Fund	4.51%
		Inflation- Protected Assets	3.52%	ŸInflation-Linked Bond Fund	3.52%
Real Estate	4.65%	Direct Real Estate	4.65%	ŸTIAA-CREF Real Property Fund LP	4.65%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2025 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 12.56%.

Best quarter: 15.33%, for the quarter ended June 30, 2009. Worst quarter: -12.93%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2025 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(6.35%)	4.14%		8.95%		Oct. 15, 2004
Institutional Class		(6.05%)	4.43%		9.23%		Jan. 17, 2007
Advisor Class		(6.19%)	4.27%	[1]	9.01%	[1]	Dec. 04, 2015
Premier Class		(6.23%)	4.27%		9.04%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(7.87%)	2.56%		7.66%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.97%)	2.90%		7.03%
S&P Target Date 2025 Index		(5.02%)	4.31%		8.46%
Lifecycle 2025 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(4.66%)	4.71%		9.00%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI All Country World Index ex USA Investable Market Index; 3.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2060 Fund

TIAA-CREF Lifecycle Index 2060 Fund

Investment objective

The Lifecycle Index 2060 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2060 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2060 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.15%	0.15%	0.15%	0.15%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.18%	0.26%	0.18%	0.43%
Total annual Fund operating expenses		0.33%	0.41%	0.48%	0.58%
Waivers and expense reimbursements	[3],[4]	(0.23%)	(0.23%)	(0.23%)	(0.23%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2060 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	83	108	131	163
5 years	162	207	246	301
10 years	$ 396	$ 495	$ 581	$ 704

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 28% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2060 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 93.75% of the Fund’s assets to equity Underlying Funds and 6.25% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2060 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2090. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 65.62%; International Equity: 28.13%; Fixed-Income: 6.25%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, for June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	94.13%	U.S. Equity	66.01%	ŸEquity Index Fund	66.01%
		International Equity	28.12%	ŸInternational Equity Index Fund	20.16%
				ŸEmerging Markets Equity Index Fund	7.96%
Fixed-Income	5.87%	Fixed-Income	5.87%	ŸBond Index Fund	5.87%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2060 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.05%.

Best quarter: 6.23%, for the quarter ended March 31, 2017. Worst quarter: -12.40%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2060 Fund		1 Year	Since Inception		Inception Date
Retirement Class		(7.33%)	5.20%		Sep. 26, 2014
Institutional Class		(7.13%)	5.45%		Sep. 26, 2014
Advisor Class		(7.16%)	5.36%	[1]	Dec. 04, 2015
Premier Class		(7.26%)	5.31%		Sep. 26, 2014
After Taxes on Distributions | Retirement Class		(7.91%)	4.48%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.97%)	3.93%
S&P Target Date 2060+ Index		(7.95%)	4.99%	[2]
Lifecycle Index 2060 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.35%)	5.51%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.06% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.04% of average daily net assets for Institutional Class shares; (ii) 0.19% of average daily net assets for Advisor Class shares; (iii) 0.19% of average daily net assets for Premier Class shares; and (iv) 0.29% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI EAFE + Emerging Markets Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifestyle Growth Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifestyle Growth Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Fund seeks long-term growth of capital with some current income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Portfolio Turnover, Rate

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29.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term growth of capital with some current income through a relatively stable asset allocation strategy targeting a growth-oriented risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 80% of the Fund’s assets in equity Underlying Funds and (2) approximately 20% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	80.45%	U.S. Equity	57.42%	ŸLarge-Cap Growth Fund	14.26%
				ŸLarge-Cap Value Fund	13.80%
				ŸGrowth & Income Fund	12.62%
				ŸQuant Large-Cap Growth Fund	7.32%
				ŸQuant Large-Cap Value Fund	4.17%
				ŸQuant Small-Cap Equity Fund	2.83%
				ŸQuant Small/Mid-Cap Equity Fund	2.42%
		International Equity	23.03%	ŸInternational Equity Fund	6.26%
				ŸInternational Opportunities Fund	5.20%
				ŸQuant International Equity Fund	4.26%
				ŸEmerging Markets Equity Fund	4.11%
				ŸQuant International Small-Cap Equity Fund	3.20%
Fixed-Income	19.55%	Fixed-Income	19.55%	ŸBond Plus Fund	19.55%

Total 100.00% 100.00% 100.00%

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a higher percentage of equity Underlying Funds, Equity Underlying Funds Risks are expected to predominate.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifestyle Growth Fund Composite Index consisted of: 56.0% Russell 3000® Index; 24.0% MSCI All Country World Index ex USA Investable Market Index; and 20.0% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Growth Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.52%.

Bar Chart Closing [Text Block]

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Best quarter: 11.87%, for the quarter ended March 31, 2012. Worst quarter: -12.86%, for the quarter ended December 31, 2018.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.52%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

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Mar. 31, 2012

Highest Quarterly Return

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11.87%

Lowest Quarterly Return, Label

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Worst quarter:

Lowest Quarterly Return, Date

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Dec. 31, 2018

Lowest Quarterly Return

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(12.86%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifestyle Growth Fund | Morningstar Moderately Aggressive Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

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1 Year

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(6.74%)

5 Years

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4.60%

Since Inception

rr_AverageAnnualReturnSinceInception

7.97%

^[1]

TIAA-CREF Lifestyle Growth Fund | Lifestyle Growth Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.38%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.20%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

8.55%

^[1],[2]

TIAA-CREF Lifestyle Growth Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.13%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.43%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.66%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

198

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

355

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 810

Annual Return 2012

rr_AnnualReturn2012

17.26%

Annual Return 2013

rr_AnnualReturn2013

23.06%

Annual Return 2014

rr_AnnualReturn2014

4.73%

Annual Return 2015

rr_AnnualReturn2015

0.34%

Annual Return 2016

rr_AnnualReturn2016

7.22%

Annual Return 2017

rr_AnnualReturn2017

21.38%

Annual Return 2018

rr_AnnualReturn2018

(9.22%)

1 Year

rr_AverageAnnualReturnYear01

(9.22%)

5 Years

rr_AverageAnnualReturnYear05

4.42%

Since Inception

rr_AverageAnnualReturnSinceInception

8.52%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Growth Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(10.40%)

5 Years

rr_AverageAnnualReturnYear05

3.20%

Since Inception

rr_AverageAnnualReturnSinceInception

7.33%

TIAA-CREF Lifestyle Growth Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.77%)

5 Years

rr_AverageAnnualReturnYear05

3.21%

Since Inception

rr_AverageAnnualReturnSinceInception

6.56%

TIAA-CREF Lifestyle Growth Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.21%

^[5]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.43%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.74%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.63%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 64

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

226

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

401

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 908

1 Year

rr_AverageAnnualReturnYear01

(9.21%)

5 Years

rr_AverageAnnualReturnYear05

4.39%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

8.50%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifestyle Growth Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.13%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.43%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.81%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.68%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 69

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

246

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

437

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 990

1 Year

rr_AverageAnnualReturnYear01

(9.30%)

5 Years

rr_AverageAnnualReturnYear05

4.25%

Since Inception

rr_AverageAnnualReturnSinceInception

8.35%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Growth Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.37%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.43%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.90%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.78%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 80

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

275

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

487

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,097

1 Year

rr_AverageAnnualReturnYear01

(9.42%)

5 Years

rr_AverageAnnualReturnYear05

4.15%

Since Inception

rr_AverageAnnualReturnSinceInception

8.25%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Growth Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.15%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.43%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.93%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

284

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

503

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,132

1 Year

rr_AverageAnnualReturnYear01

(9.47%)

5 Years

rr_AverageAnnualReturnYear05

4.11%

Since Inception

rr_AverageAnnualReturnSinceInception

8.20%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

[1] Performance is calculated from the inception date of the Institutional Class.

[2] As of the close of business on December 31, 2018, the Lifestyle Growth Fund Composite Index consisted of: 56.0% Russell 3000® Index; 24.0% MSCI All Country World Index ex USA Investable Market Index; and 20.0% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[5] Restated to reflect estimate for the current fiscal year.

[6] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2045 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2045 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2045 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

4.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2045 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 90.00% of the Fund’s assets to equity Underlying Funds and 10.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2045 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2075. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.00%; International Equity: 27.00%; Fixed-Income: 10.00; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	90.44%	U.S. Equity	63.43%	ŸEquity Index Fund	63.43%
		International Equity	27.01%	ŸInternational Equity Index Fund	19.37%
				ŸEmerging Markets Equity Index Fund	7.64%
Fixed-Income	9.56%	Fixed-Income	9.56%	ŸBond Index Fund	9.56%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI EAFE + Emerging Markets Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2045 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.76%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 11.95%, for the quarter ended September 30, 2010. Worst quarter: -14.77%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.76%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.95%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.77%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2045 Fund | S&P Target Date 2045 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.74%)

5 Years

rr_AverageAnnualReturnYear05

4.91%

Since Inception

rr_AverageAnnualReturnSinceInception

8.49%

^[1]

TIAA-CREF Lifecycle Index 2045 Fund | Lifecycle Index 2045 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.03%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.59%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

9.10%

^[1],[2]

TIAA-CREF Lifecycle Index 2045 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.19%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

52

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

98

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 234

1 Year

rr_AverageAnnualReturnYear01

(6.92%)

5 Years

rr_AverageAnnualReturnYear05

5.52%

Since Inception

rr_AverageAnnualReturnSinceInception

8.98%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2045 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.29%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 19

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

83

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

153

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 358

1 Year

rr_AverageAnnualReturnYear01

(7.04%)

5 Years

rr_AverageAnnualReturnYear05

5.38%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

8.78%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2045 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.34%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

182

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 422

1 Year

rr_AverageAnnualReturnYear01

(7.04%)

5 Years

rr_AverageAnnualReturnYear05

5.37%

Since Inception

rr_AverageAnnualReturnSinceInception

8.83%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2045 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.44%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

237

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 546

Annual Return 2010

rr_AnnualReturn2010

13.50%

Annual Return 2011

rr_AnnualReturn2011

(1.61%)

Annual Return 2012

rr_AnnualReturn2012

15.38%

Annual Return 2013

rr_AnnualReturn2013

24.86%

Annual Return 2014

rr_AnnualReturn2014

6.56%

Annual Return 2015

rr_AnnualReturn2015

(0.97%)

Annual Return 2016

rr_AnnualReturn2016

9.04%

Annual Return 2017

rr_AnnualReturn2017

20.89%

Annual Return 2018

rr_AnnualReturn2018

(7.12%)

1 Year

rr_AverageAnnualReturnYear01

(7.12%)

5 Years

rr_AverageAnnualReturnYear05

5.26%

Since Inception

rr_AverageAnnualReturnSinceInception

8.72%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2045 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.67%)

5 Years

rr_AverageAnnualReturnYear05

4.66%

Since Inception

rr_AverageAnnualReturnSinceInception

8.19%

TIAA-CREF Lifecycle Index 2045 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.87%)

5 Years

rr_AverageAnnualReturnYear05

4.01%

Since Inception

rr_AverageAnnualReturnSinceInception

7.02%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI EAFE + Emerging Markets Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.062% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.038% of average daily net assets for Institutional Class shares; (ii) 0.188% of average daily net assets for Advisor Class shares; (iii) 0.188% of average daily net assets for Premier Class shares; and (iv) 0.288% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

TIAA-CREF Lifecycle Index 2030 Fund

TIAA-CREF Lifecycle Index 2030 Fund

Investment objective

The Lifecycle Index 2030 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2030 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2030 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.17%	0.17%	0.17%	0.17%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.12%	0.03%	0.28%
Total annual Fund operating expenses		0.20%	0.29%	0.35%	0.45%
Waivers and expense reimbursements	[3],[4]	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.19%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2030 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 19	$ 26	$ 36
3 years	54	83	102	134
5 years	103	153	186	242
10 years	$ 245	$ 358	$ 433	$ 557

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 10% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2030 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 66.00% of the Fund’s assets to equity Underlying Funds and 34.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2030 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2060. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 46.20%; International Equity: 19.80%; Fixed-Income: 30.00%; Short-Term Fixed-Income: 2.00%; and Inflation-Protected Assets: 2.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	68.26%	U.S. Equity	47.88%	ŸEquity Index Fund	47.88%
		International Equity	20.38%	ŸInternational Equity Index Fund	14.61%
				ŸEmerging Markets Equity Index Fund	5.77%
Fixed-Income	31.74%	Fixed-Income	28.64%	ŸBond Index Fund	28.64%
		Short-Term Fixed-Income	1.55%	ŸShort-Term Bond Index Fund	1.55%
		Inflation- Protected Assets	1.55%	ŸInflation-Linked Bond Fund	1.55%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2030 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.26%.

Best quarter: 11.08%, for the quarter ended September 30, 2010. Worst quarter: -12.86%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2030 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(5.27%)	4.71%		7.90%		Sep. 30, 2009
Institutional Class		(5.04%)	4.97%		8.17%		Sep. 30, 2009
Advisor Class		(5.14%)	4.82%	[1]	7.96%	[1]	Dec. 04, 2015
Premier Class		(5.21%)	4.82%		8.01%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(5.91%)	4.06%		7.34%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.85%)	3.51%		6.28%
S&P Target Date 2030 Index		(5.99%)	4.50%		7.71%	[2]
Lifecycle Index 2030 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(5.17%)	5.04%		8.28%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.075% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.025% of average daily net assets for Institutional Class shares; (ii) 0.175% of average daily net assets for Advisor Class shares; (iii) 0.175% of average daily net assets for Premier Class shares; and (iv) 0.275% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI EAFE + Emerging Markets Index; 1.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index Retirement Income Fund

TIAA-CREF Lifecycle Index Retirement Income Fund

Investment objective

The Lifecycle Index Retirement Income Fund seeks high total return over time primarily through income,

with a secondary emphasis on capital appreciation.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index Retirement Income Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum Sales Charge Imposed on Purchases (percentage of offering price)	none	none	none	none
Maximum Deferred Sales Charge	none	none	none	none
Maximum Sales Charge Imposed on Reinvested Dividends and Other Distributions	none	none	none	none
Redemption or Exchange Fee	none	none	none	none
Maximum Account Fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index Retirement Income Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.19%	0.19%	0.19%	0.19%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.09%	0.17%	0.08%	0.34%
Total annual Fund operating expenses		0.28%	0.36%	0.42%	0.53%
Waivers and expense reimbursements	[3],[4]	(0.18%)	(0.18%)	(0.17%)	(0.18%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index Retirement Income Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	72	97	118	152
5 years	139	184	218	278
10 years	$ 338	$ 438	$ 513	$ 648

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy that will not gradually adjust over time and is designed for investors who are already in retirement (i.e., have already passed their retirement year) and may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets in Underlying Funds that are managed to seek investment returns that track particular market indices. For purposes of the 80% investment policy, the term “assets” means net assets, plus the amount of any borrowings for investment purposes.

Advisors currently expects to allocate approximately 40% of the Fund’s assets to equity Underlying Funds and 60% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations may be changed and actual allocations may vary up to ten percentage points from the targets. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which may change, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; and Inflation-Protected Assets: 10.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income) and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change. Investors should note that the Fund has a significant level of equity exposure and this exposure could cause fluctuation in the value of the Fund depending on the performance of the equity markets generally.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. The Fund has relatively fixed asset allocations that will not gradually adjust over time. Underlying Fund allocations may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	40.69%	U.S. Equity	28.54%	ŸEquity Index Fund	28.54%
		International Equity	12.15%	ŸInternational Equity Index Fund	8.71%
				ŸEmerging Markets Equity Index Fund	3.44%
Fixed-Income	59.31%	Fixed-Income	39.57%	ŸBond Index Fund	39.57%
		Short-Term Fixed-Income	9.85%	ŸShort-Term Bond Index Fund	9.85%
		Inflation- Protected Assets	9.89%	ŸInflation-Linked Bond Fund	9.89%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index Retirement Income Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 9.85%.

Best quarter: 6.74%, for the quarter ended September 30, 2010. Worst quarter: -4.69%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index Retirement Income Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(2.90%)	3.52%		5.49%		Sep. 30, 2009
Institutional Class		(2.65%)	3.79%		5.76%		Sep. 30, 2009
Advisor Class		(2.67%)	3.66%	[1]	5.57%	[1]	Dec. 04, 2015
Premier Class		(2.80%)	3.62%		5.60%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(3.74%)	2.78%		4.77%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(1.52%)	2.47%		4.12%
S&P Target Date Retirement Income Index		(2.54%)	3.06%		4.75%	[2]
Lifecycle Index Retirement Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(2.83%)	3.84%		5.88%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.102% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI EAFE + Emerging Markets Index; 10.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2055 Fund

TIAA-CREF Lifecycle 2055 Fund

Investment objective

The Lifecycle 2055 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2055 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2055 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.50%	0.50%	0.50%	0.50%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.06%	0.14%	0.06%	0.31%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.59%	0.67%	0.74%	0.84%
Waivers and expense reimbursements	[4],[5]	(0.14%)	(0.14%)	(0.14%)	(0.14%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.45%	0.53%	0.60%	0.70%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2055 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 46	$ 54	$ 61	$ 72
3 years	153	179	201	233
5 years	294	338	376	431
10 years	$ 704	$ 801	$ 885	$ 1,004

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 10% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2055 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 92.50% of the Fund’s assets to equity Underlying Funds, 2.50% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2055 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2085. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 64.75%; International Equity: 27.75%; Fixed-Income: 2.50%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	92.85%	U.S. Equity	65.09%	ŸGrowth & Income Fund	13.65%
				ŸLarge-Cap Growth Fund	12.32%
				ŸLarge-Cap Value Fund	11.94%
				ŸQuant Large-Cap Growth Fund	10.76%
				ŸQuant Large-Cap Value Fund	10.46%
				ŸQuant Small-Cap Equity Fund	3.34%
				ŸQuant Small/Mid-Cap Equity Fund	2.62%
		International Equity	27.76%	ŸQuant International Equity Fund	7.25%
				ŸInternational Equity Fund	6.04%
				ŸInternational Opportunities Fund	6.02%
				ŸEmerging Markets Equity Fund	4.75%
				ŸQuant International Small-Cap Equity Fund	3.70%
Fixed-Income	2.55%	Fixed-Income	2.55%	ŸBond Fund	1.34%
				ŸBond Plus Fund	0.83%
				ŸEmerging Markets Debt Fund	0.19%
				ŸInternational Bond Fund	0.13%
				ŸHigh-Yield Fund	0.06%
Real Estate	4.60%	Direct Real Estate	4.60%	ŸTIAA-CREF Real Property Fund LP	4.60%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2055 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.40%.

Best quarter: 12.82%, for the quarter ended March 31, 2012. Worst quarter: -14.52%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2055 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(10.13%)	4.63%		6.64%		Apr. 29, 2011
Institutional Class		(9.86%)	4.89%		6.91%		Apr. 29, 2011
Advisor Class		(9.87%)	4.79%	[1]	6.75%	[1]	Dec. 04, 2015
Premier Class		(10.10%)	4.72%		6.74%		Apr. 29, 2011
After Taxes on Distributions | Retirement Class		(11.10%)	3.53%		5.61%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(5.40%)	3.41%		5.06%
S&P Target Date 2055 Index		(7.97%)	5.07%		6.82%	[2]
Lifecycle 2055 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.48%)	5.65%		7.40%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.Performance is calculated from the inception date of the Retirement Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI All Country World Index ex USA Investable Market Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2015 Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifecycle Index 2015 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle Index 2015 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

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17.00%

Expenses Restated to Reflect Current [Text]

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Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2015 and who may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 45.00% of the Fund’s assets to equity Underlying Funds and 55.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2015 and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2045. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020 which will change over time, are approximately as follows: U.S. Equity: 31.50%; International Equity: 13.50%; Fixed-Income: 39.00%; Short-Term Fixed-Income: 8.00%; and Inflation-Protected Assets: 8.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	46.75%	U.S. Equity	32.79%	ŸEquity Index Fund	32.79%
		International Equity	13.96%	ŸInternational Equity Index Fund	10.01%
				ŸEmerging Markets Equity Index Fund	3.95%
Fixed-Income	53.25%	Fixed-Income	38.30%	ŸBond Index Fund	38.30%
		Short-Term Fixed-Income	7.46%	ŸShort-Term Bond Index Fund	7.46%
		Inflation- Protected Assets	7.49%	ŸInflation-Linked Bond Fund	7.49%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifecycle Index 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI EAFE + Emerging Markets Index; 7.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2015 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.65%.

Bar Chart Closing [Text Block]

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Best quarter: 8.63%, for the quarter ended September 30, 2010. Worst quarter: -8.09%, for the quarter ended September 30, 2011.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

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Jun. 30, 2019

Bar Chart, Year to Date Return

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10.65%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

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Sep. 30, 2010

Highest Quarterly Return

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8.63%

Lowest Quarterly Return, Label

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Worst quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(8.09%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2015 Fund | S&P Target Date 2015 Index

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

(3.67%)

5 Years

rr_AverageAnnualReturnYear05

3.79%

Since Inception

rr_AverageAnnualReturnSinceInception

6.21%

^[1]

TIAA-CREF Lifecycle Index 2015 Fund | Lifecycle Index 2015 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.36%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.21%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

6.74%

^[1],[2]

TIAA-CREF Lifecycle Index 2015 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.05%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.23%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

61

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

116

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 280

1 Year

rr_AverageAnnualReturnYear01

(3.29%)

5 Years

rr_AverageAnnualReturnYear05

4.14%

Since Inception

rr_AverageAnnualReturnSinceInception

6.61%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2015 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.13%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.31%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

87

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

161

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 381

1 Year

rr_AverageAnnualReturnYear01

(3.31%)

5 Years

rr_AverageAnnualReturnYear05

4.04%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

6.43%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2015 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.05%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.38%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

109

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

200

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 468

1 Year

rr_AverageAnnualReturnYear01

(3.45%)

5 Years

rr_AverageAnnualReturnYear05

3.98%

Since Inception

rr_AverageAnnualReturnSinceInception

6.45%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2015 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.18%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.30%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.48%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

141

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

256

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 591

Annual Return 2010

rr_AnnualReturn2010

11.03%

Annual Return 2011

rr_AnnualReturn2011

2.28%

Annual Return 2012

rr_AnnualReturn2012

11.07%

Annual Return 2013

rr_AnnualReturn2013

12.54%

Annual Return 2014

rr_AnnualReturn2014

6.07%

Annual Return 2015

rr_AnnualReturn2015

(0.28%)

Annual Return 2016

rr_AnnualReturn2016

5.87%

Annual Return 2017

rr_AnnualReturn2017

11.97%

Annual Return 2018

rr_AnnualReturn2018

(3.50%)

1 Year

rr_AverageAnnualReturnYear01

(3.50%)

5 Years

rr_AverageAnnualReturnYear05

3.89%

Since Inception

rr_AverageAnnualReturnSinceInception

6.35%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2015 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.37%)

5 Years

rr_AverageAnnualReturnYear05

3.14%

Since Inception

rr_AverageAnnualReturnSinceInception

5.70%

TIAA-CREF Lifecycle Index 2015 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.81%)

5 Years

rr_AverageAnnualReturnYear05

2.78%

Since Inception

rr_AverageAnnualReturnSinceInception

4.89%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI EAFE + Emerging Markets Index; 7.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.095% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.005% of average daily net assets for Institutional Class shares; (ii) 0.155% of average daily net assets for Advisor Class shares; (iii) 0.155% of average daily net assets for Premier Class shares; and (iv) 0.255% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

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TIAA-CREF Lifecycle 2040 Fund

TIAA-CREF Lifecycle 2040 Fund

Investment objective

The Lifecycle 2040 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2040 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2040 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.49%	0.49%	0.49%	0.49%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.55%	0.63%	0.70%	0.80%
Waivers and expense reimbursements	[4],[5]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.44%	0.52%	0.59%	0.69%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2040 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 45	$ 53	$ 60	$ 70
3 years	143	169	191	223
5 years	275	319	357	412
10 years	$ 658	$ 755	$ 840	$ 959

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 18% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2040 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 81.00% of the Fund’s assets to equity Underlying Funds, 14.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2040 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2070. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 56.70%; International Equity: 24.30%; Fixed-Income: 14.00%; Short-Term Fixed-Income: 0.00; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	83.23%	U.S. Equity	58.36%	ŸGrowth & Income Fund	12.22%
				ŸLarge-Cap Growth Fund	11.05%
				ŸLarge-Cap Value Fund	10.71%
				ŸQuant Large-Cap Growth Fund	9.65%
				ŸQuant Large-Cap Value Fund	9.38%
				ŸQuant Small-Cap Equity Fund	3.00%
				ŸQuant Small/Mid-Cap Equity Fund	2.35%
		International Equity	24.87%	ŸQuant International Equity Fund	6.49%
				ŸInternational Equity Fund	5.41%
				ŸInternational Opportunities Fund	5.40%
				ŸEmerging Markets Equity Fund	4.26%
				ŸQuant International Small-Cap Equity Fund	3.31%
Fixed-Income	12.14%	Fixed-Income	12.14%	ŸBond Fund	6.37%
				ŸBond Plus Fund	3.94%
				ŸEmerging Markets Debt Fund	0.83%
				ŸInternational Bond Fund	0.64%
				ŸHigh-Yield Fund	0.36%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2040 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.53%.

Best quarter: 17.54%, for the quarter ended June 30, 2009. Worst quarter: -16.45%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2040 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(9.17%)	4.53%		10.11%		Oct. 15, 2004
Institutional Class		(8.92%)	4.79%		10.39%		Jan. 17, 2007
Advisor Class		(8.97%)	4.66%	[1]	10.19%	[1]	Dec. 04, 2015
Premier Class		(9.11%)	4.62%		10.22%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(10.67%)	2.95%		8.86%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(4.45%)	3.30%		8.13%
S&P Target Date 2040 Index		(7.41%)	4.82%		9.68%
Lifecycle 2040 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(6.72%)	5.45%		10.44%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI All Country World Index ex USA Investable Market Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2055 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2055 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2055 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

4.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2055 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 92.50% of the Fund’s assets to equity Underlying Funds and 7.50% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2055 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2085. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 64.75%; International Equity: 27.75%; Fixed-Income: 7.50%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Market Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	92.91%	U.S. Equity	65.16%	ŸEquity Index Fund	65.16%
		International Equity	27.75%	ŸInternational Equity Index Fund	19.90%
				ŸEmerging Markets Equity Index Fund	7.85%
Fixed-Income	7.09%	Fixed-Income	7.09%	ŸBond Index Fund	7.09%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI EAFE + Emerging Markets Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2055 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.96%.

Bar Chart Closing [Text Block]

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Best quarter: 11.36%, for the quarter ended March 31, 2012. Worst quarter: -12.23%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.96%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.36%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(12.23%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2055 Fund | S&P Target Date 2055 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.97%)

5 Years

rr_AverageAnnualReturnYear05

5.07%

Since Inception

rr_AverageAnnualReturnSinceInception

6.82%

^[1]

TIAA-CREF Lifecycle Index 2055 Fund | Lifecycle Index 2055 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.24%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.71%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

7.45%

^[1],[2]

TIAA-CREF Lifecycle Index 2055 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.07%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.22%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

59

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

112

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 268

1 Year

rr_AverageAnnualReturnYear01

(7.14%)

5 Years

rr_AverageAnnualReturnYear05

5.64%

Since Inception

rr_AverageAnnualReturnSinceInception

7.36%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle Index 2055 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.15%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.30%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

84

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

157

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 369

1 Year

rr_AverageAnnualReturnYear01

(7.11%)

5 Years

rr_AverageAnnualReturnYear05

5.53%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

7.19%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2055 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.06%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.36%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

105

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

191

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 445

1 Year

rr_AverageAnnualReturnYear01

(7.21%)

5 Years

rr_AverageAnnualReturnYear05

5.50%

Since Inception

rr_AverageAnnualReturnSinceInception

7.21%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle Index 2055 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.31%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.46%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

137

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

247

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 569

Annual Return 2012

rr_AnnualReturn2012

15.36%

Annual Return 2013

rr_AnnualReturn2013

24.93%

Annual Return 2014

rr_AnnualReturn2014

6.62%

Annual Return 2015

rr_AnnualReturn2015

(1.00%)

Annual Return 2016

rr_AnnualReturn2016

9.42%

Annual Return 2017

rr_AnnualReturn2017

21.47%

Annual Return 2018

rr_AnnualReturn2018

(7.32%)

1 Year

rr_AverageAnnualReturnYear01

(7.32%)

5 Years

rr_AverageAnnualReturnYear05

5.39%

Since Inception

rr_AverageAnnualReturnSinceInception

7.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle Index 2055 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.86%)

5 Years

rr_AverageAnnualReturnYear05

4.81%

Since Inception

rr_AverageAnnualReturnSinceInception

6.55%

TIAA-CREF Lifecycle Index 2055 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.00%)

5 Years

rr_AverageAnnualReturnYear05

4.12%

Since Inception

rr_AverageAnnualReturnSinceInception

5.58%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI EAFE + Emerging Markets Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.06% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.04% of average daily net assets for Institutional Class shares; (ii) 0.19% of average daily net assets for Advisor Class shares; (iii) 0.19% of average daily net assets for Premier Class shares; and (iv) 0.29% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2040 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2040 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2040 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 6% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

6.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2040 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 82.00% of the Fund’s assets to equity Underlying Funds and 18.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2040 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2070. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 57.40%; International Equity: 24.60%; Fixed-Income: 18.00%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	84.01%	U.S. Equity	58.92%	ŸEquity Index Fund	58.92%
		International Equity	25.09%	ŸInternational Equity Index Fund	17.99%
				ŸEmerging Markets Equity Index Fund	7.10%
Fixed-Income	15.99%	Fixed-Income	15.99%	ŸBond Index Fund	15.99%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI EAFE + Emerging Markets Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2040 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.08%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 11.87%, for the quarter ended September 30, 2010. Worst quarter: -14.82%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.08%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.82%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2040 Fund | S&P Target Date 2040 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.41%)

5 Years

rr_AverageAnnualReturnYear05

4.82%

Since Inception

rr_AverageAnnualReturnSinceInception

8.31%

^[1]

TIAA-CREF Lifecycle Index 2040 Fund | Lifecycle Index 2040 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.50%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.51%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

9.06%

^[1],[2]

TIAA-CREF Lifecycle Index 2040 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.19%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

52

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

98

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 234

1 Year

rr_AverageAnnualReturnYear01

(6.36%)

5 Years

rr_AverageAnnualReturnYear05

5.45%

Since Inception

rr_AverageAnnualReturnSinceInception

8.95%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2040 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.27%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

78

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

143

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 334

1 Year

rr_AverageAnnualReturnYear01

(6.42%)

5 Years

rr_AverageAnnualReturnYear05

5.31%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

8.75%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2040 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.34%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

182

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 422

1 Year

rr_AverageAnnualReturnYear01

(6.53%)

5 Years

rr_AverageAnnualReturnYear05

5.29%

Since Inception

rr_AverageAnnualReturnSinceInception

8.78%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2040 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.16%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.44%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

237

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 546

Annual Return 2010

rr_AnnualReturn2010

13.50%

Annual Return 2011

rr_AnnualReturn2011

(1.70%)

Annual Return 2012

rr_AnnualReturn2012

15.46%

Annual Return 2013

rr_AnnualReturn2013

24.87%

Annual Return 2014

rr_AnnualReturn2014

6.56%

Annual Return 2015

rr_AnnualReturn2015

(0.93%)

Annual Return 2016

rr_AnnualReturn2016

8.74%

Annual Return 2017

rr_AnnualReturn2017

20.08%

Annual Return 2018

rr_AnnualReturn2018

(6.60%)

1 Year

rr_AverageAnnualReturnYear01

(6.60%)

5 Years

rr_AverageAnnualReturnYear05

5.18%

Since Inception

rr_AverageAnnualReturnSinceInception

8.68%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2040 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.17%)

5 Years

rr_AverageAnnualReturnYear05

4.56%

Since Inception

rr_AverageAnnualReturnSinceInception

8.15%

TIAA-CREF Lifecycle Index 2040 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.58%)

5 Years

rr_AverageAnnualReturnYear05

3.94%

Since Inception

rr_AverageAnnualReturnSinceInception

6.98%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI EAFE + Emerging Markets Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.065% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.035% of average daily net assets for Institutional Class shares; (ii) 0.185% of average daily net assets for Advisor Class shares; (iii) 0.185% of average daily net assets for Premier Class shares; and (iv) 0.285% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

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TIAA-CREF Lifecycle Index 2050 Fund

TIAA-CREF Lifecycle Index 2050 Fund

Investment objective

The Lifecycle Index 2050 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2050 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2050 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.15%	0.15%	0.15%	0.15%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.13%	0.04%	0.29%
Total annual Fund operating expenses		0.19%	0.28%	0.34%	0.44%
Waivers and expense reimbursements	[3],[4]	(0.09%)	(0.10%)	(0.09%)	(0.09%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2050 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	52	80	100	132
5 years	98	147	182	237
10 years	$ 234	$ 346	$ 422	$ 546

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 5% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2050 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 91.25% of the Fund’s assets to equity Underlying Funds and 8.75% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2050 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2080. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.87%; International Equity: 27.38%; Fixed-Income: 8.75%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	91.65%	U.S. Equity	64.27%	ŸEquity Index Fund	64.27%
		International Equity	27.38%	ŸInternational Equity Index Fund	19.63%
				ŸEmerging Markets Equity Index Fund	7.75%
Fixed-Income	8.35%	Fixed-Income	8.35%	ŸBond Index Fund	8.35%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2050 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.90%.

Best quarter: 11.85%, for the quarter ended September 30, 2010. Worst quarter: -14.85%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2050 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(7.26%)	5.32%		8.76%		Sep. 30, 2009
Institutional Class		(7.01%)	5.59%		9.03%		Sep. 30, 2009
Advisor Class		(7.05%)	5.45%	[1]	8.83%	[1]	Dec. 04, 2015
Premier Class		(7.13%)	5.43%		8.87%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(7.80%)	4.72%		8.23%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.95%)	4.06%		7.05%
S&P Target Date 2050 Index		(7.94%)	5.01%		8.64%	[2]
Lifecycle Index 2050 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.14%)	5.65%		9.14%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.061% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.039% of average daily net assets for Institutional Class shares; (ii) 0.189% of average daily net assets for Advisor Class shares; (iii) 0.189% of average daily net assets for Premier Class shares; and (iv) 0.289% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI EAFE + Emerging Markets Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2015 Fund

TIAA-CREF Lifecycle 2015 Fund

Investment objective

The Lifecycle 2015 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2015 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2015 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.43%	0.43%	0.43%	0.43%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.12%	0.04%	0.29%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.50%	0.58%	0.65%	0.75%
Waivers and expense reimbursements	[4],[5]	(0.12%)	(0.12%)	(0.12%)	(0.12%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.38%	0.46%	0.53%	0.63%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2015 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 39	$ 47	$ 54	$ 64
3 years	126	152	174	206
5 years	246	290	329	384
10 years	$ 596	$ 694	$ 779	$ 899

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 21% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2015 and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 40.00% of the Fund’s assets to equity Underlying Funds, 55.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2015 (the direct real estate asset class was added in 2017) and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2045. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 39.00%; Short-Term Fixed-Income: 8.00%; Inflation-Protected Assets: 8.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	42.07%	U.S. Equity	29.51%	ŸGrowth & Income Fund	6.18%
				ŸLarge-Cap Growth Fund	5.59%
				ŸLarge-Cap Value Fund	5.42%
				ŸQuant Large-Cap Growth Fund	4.88%
				ŸQuant Large-Cap Value Fund	4.74%
				ŸQuant Small-Cap Equity Fund	1.51%
				ŸQuant Small/Mid-Cap Equity Fund	1.19%
		International Equity	12.56%	ŸQuant International Equity Fund	3.28%
				ŸInternational Equity Fund	2.73%
				ŸInternational Opportunities Fund	2.72%
				ŸEmerging Markets Equity Fund	2.15%
				ŸQuant International Small-Cap Equity Fund	1.68%
Fixed-Income	53.25%	Fixed-Income	37.34%	ŸBond Fund	19.13%
				ŸBond Plus Fund	12.48%
				ŸEmerging Markets Debt Fund	2.07%
				ŸInternational Bond Fund	2.00%
				ŸHigh-Yield Fund	1.66%
		Short-Term Fixed-Income	8.45%	ŸShort-Term Bond Fund	8.45%
		Inflation- Protected Assets	7.46%	ŸInflation-Linked Bond Fund	7.46%
Real Estate	4.68%	Direct Real Estate	4.68%	ŸTIAA-CREF Real Property Fund LP	4.68%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2015 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.78%.

Best quarter: 12.39%, for the quarter ended June 30, 2009. Worst quarter: -9.52%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2015 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(4.74%)	3.75%		7.80%		Oct. 15, 2004
Institutional Class		(4.41%)	4.03%		8.08%		Jan. 17, 2007
Advisor Class		(4.42%)	3.91%	[1]	7.88%	[1]	Dec. 04, 2015
Premier Class		(4.60%)	3.87%		7.90%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(6.36%)	2.05%		6.39%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.07%)	2.54%		5.99%
S&P Target Date 2015 Index		(3.67%)	3.79%		7.11%
Lifecycle 2015 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(3.48%)	4.12%		7.74%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI All Country World Index ex USA Investable Market Index; 7.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2035 Fund

TIAA-CREF Lifecycle Index 2035 Fund

Investment objective

The Lifecycle Index 2035 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2035 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2035 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.16%	0.16%	0.16%	0.16%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.12%	0.03%	0.28%
Total annual Fund operating expenses		0.19%	0.28%	0.34%	0.44%
Waivers and expense reimbursements	[3],[4]	(0.09%)	(0.09%)	(0.09%)	(0.09%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.19%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2035 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 19	$ 26	$ 36
3 years	52	81	100	132
5 years	98	148	182	237
10 years	$ 234	$ 347	$ 422	$ 546

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2035 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 74.00% of the Fund’s assets to equity Underlying Funds and 26.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2035 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2065. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 51.80%; International Equity: 22.20%; Fixed-Income: 26.00%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	76.16%	U.S. Equity	53.41%	ŸEquity Index Fund	53.41%
		International Equity	22.75%	ŸInternational Equity Index Fund	16.31%
				ŸEmerging Markets Equity Index Fund	6.44%
Fixed-Income	23.84%	Fixed-Income	23.84%	ŸBond Index Fund	23.84%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2035 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 14.20%.

Best quarter: 11.89%, for the quarter ended September 30, 2010. Worst quarter: -14.45%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2035 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(5.92%)	4.96%		8.38%		Sep. 30, 2009
Institutional Class		(5.73%)	5.22%		8.65%		Sep. 30, 2009
Advisor Class		(5.77%)	5.10%	[1]	8.45%	[1]	Dec. 04, 2015
Premier Class		(5.90%)	5.06%		8.48%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(6.54%)	4.33%		7.84%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.20%)	3.74%		6.71%
S&P Target Date 2035 Index		(6.88%)	4.69%		8.06%	[2]
Lifecycle Index 2035 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(5.83%)	5.28%		8.76%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.069% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.031% of average daily net assets for Institutional Class shares; (ii) 0.181% of average daily net assets for Advisor Class shares; (iii) 0.181% of average daily net assets for Premier Class shares; and (iv) 0.281% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI EAFE + Emerging Markets Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2025 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2025 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2025 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 11% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

11.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2025 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 58.00% of the Fund’s assets to equity Underlying Funds and 42.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2025 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2055. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 40.60%; International Equity: 17.40%; Fixed-Income: 34.00%; Short-Term Fixed-Income: 4.00%; and Inflation-Protected Assets: 4.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.34%	U.S. Equity	42.32%	ŸEquity Index Fund	42.32%
		International Equity	18.02%	ŸInternational Equity Index Fund	12.92%
				ŸEmerging Markets Equity Index Fund	5.10%
Fixed-Income	39.66%	Fixed-Income	32.62%	ŸBond Index Fund	32.62%
		Short-Term Fixed-Income	3.51%	ŸShort-Term Bond Index Fund	3.51%
		Inflation- Protected Assets	3.53%	ŸInflation-Linked Bond Fund	3.53%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI EAFE + Emerging Markets Index; 3.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2025 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 12.34%.

Bar Chart Closing [Text Block]

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Best quarter: 10.18%, for the quarter ended September 30, 2010. Worst quarter: -11.34%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

12.34%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

10.18%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(11.34%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2025 Fund | S&P Target Date 2025 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.02%)

5 Years

rr_AverageAnnualReturnYear05

4.31%

Since Inception

rr_AverageAnnualReturnSinceInception

7.31%

^[1]

TIAA-CREF Lifecycle Index 2025 Fund | Lifecycle Index 2025 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.49%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.77%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

7.77%

^[1],[2]

TIAA-CREF Lifecycle Index 2025 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.21%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

56

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

107

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 257

1 Year

rr_AverageAnnualReturnYear01

(4.42%)

5 Years

rr_AverageAnnualReturnYear05

4.70%

Since Inception

rr_AverageAnnualReturnSinceInception

7.65%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2025 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.31%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.20%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 20

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

89

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

163

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 382

1 Year

rr_AverageAnnualReturnYear01

(4.49%)

5 Years

rr_AverageAnnualReturnYear05

4.56%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

7.45%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2025 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.36%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

105

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

191

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 445

1 Year

rr_AverageAnnualReturnYear01

(4.58%)

5 Years

rr_AverageAnnualReturnYear05

4.53%

Since Inception

rr_AverageAnnualReturnSinceInception

7.49%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2025 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.46%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

137

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

247

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 569

Annual Return 2010

rr_AnnualReturn2010

12.31%

Annual Return 2011

rr_AnnualReturn2011

0.38%

Annual Return 2012

rr_AnnualReturn2012

13.00%

Annual Return 2013

rr_AnnualReturn2013

17.87%

Annual Return 2014

rr_AnnualReturn2014

6.39%

Annual Return 2015

rr_AnnualReturn2015

(0.52%)

Annual Return 2016

rr_AnnualReturn2016

7.00%

Annual Return 2017

rr_AnnualReturn2017

15.09%

Annual Return 2018

rr_AnnualReturn2018

(4.65%)

1 Year

rr_AverageAnnualReturnYear01

(4.65%)

5 Years

rr_AverageAnnualReturnYear05

4.44%

Since Inception

rr_AverageAnnualReturnSinceInception

7.38%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2025 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.34%)

5 Years

rr_AverageAnnualReturnYear05

3.78%

Since Inception

rr_AverageAnnualReturnSinceInception

6.81%

TIAA-CREF Lifecycle Index 2025 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.51%)

5 Years

rr_AverageAnnualReturnYear05

3.28%

Since Inception

rr_AverageAnnualReturnSinceInception

5.82%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI EAFE + Emerging Markets Index; 3.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.082% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.018% of average daily net assets for Institutional Class shares; (ii) 0.168% of average daily net assets for Advisor Class shares; (iii) 0.168% of average daily net assets for Premier Class shares; and (iv) 0.268% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2035 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2035 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2035 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

17.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2035 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 72.00% of the Fund’s assets to equity Underlying Funds, 23.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2035 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2065. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 50.40%; International Equity: 21.60%; Fixed-Income: 23.00%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00% and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	74.44%	U.S. Equity	52.20%	ŸGrowth & Income Fund	10.93%
				ŸLarge-Cap Growth Fund	9.89%
				ŸLarge-Cap Value Fund	9.58%
				ŸQuant Large-Cap Growth Fund	8.63%
				ŸQuant Large-Cap Value Fund	8.39%
				ŸQuant Small-Cap Equity Fund	2.68%
				ŸQuant Small/Mid-Cap Equity Fund	2.10%
		International Equity	22.24%	ŸQuant International Equity Fund	5.81%
				ŸInternational Equity Fund	4.84%
				ŸInternational Opportunities Fund	4.82%
				ŸEmerging Markets Equity Fund	3.81%
				ŸQuant International Small-Cap Equity Fund	2.96%
Fixed-Income	20.93%	Fixed-Income	20.93%	ŸBond Fund	10.99%
				ŸBond Plus Fund	6.80%
				ŸEmerging Markets Debt Fund	1.25%
				ŸInternational Bond Fund	1.09%
				ŸHigh-Yield Fund	0.80%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2035 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 14.56%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 17.55%, for the quarter ended June 30, 2009. Worst quarter: -16.14%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

14.56%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.14%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

 
After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2035 Fund | S&P Target Date 2035 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.88%)

5 Years

rr_AverageAnnualReturnYear05

4.69%

10 Years

rr_AverageAnnualReturnYear10

9.38%

TIAA-CREF Lifecycle 2035 Fund | Lifecycle 2035 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.03%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

5.23%

^[1]

10 Years

rr_AverageAnnualReturnYear10

10.17%

^[1]

TIAA-CREF Lifecycle 2035 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.48%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.54%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.43%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 44

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

140

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

269

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 646

1 Year

rr_AverageAnnualReturnYear01

(8.04%)

5 Years

rr_AverageAnnualReturnYear05

4.67%

10 Years

rr_AverageAnnualReturnYear10

10.17%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2035 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.48%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.62%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.51%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 52

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

166

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

313

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 743

1 Year

rr_AverageAnnualReturnYear01

(7.98%)

5 Years

rr_AverageAnnualReturnYear05

4.56%

^[7]

10 Years

rr_AverageAnnualReturnYear10

9.98%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2035 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.48%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.69%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.58%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 59

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

188

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

352

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 828

1 Year

rr_AverageAnnualReturnYear01

(8.12%)

5 Years

rr_AverageAnnualReturnYear05

4.53%

10 Years

rr_AverageAnnualReturnYear10

10.02%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2035 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.48%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.79%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.68%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 69

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

220

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

407

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 947

Annual Return 2009

rr_AnnualReturn2009

28.30%

Annual Return 2010

rr_AnnualReturn2010

15.02%

Annual Return 2011

rr_AnnualReturn2011

(3.55%)

Annual Return 2012

rr_AnnualReturn2012

17.01%

Annual Return 2013

rr_AnnualReturn2013

24.40%

Annual Return 2014

rr_AnnualReturn2014

4.42%

Annual Return 2015

rr_AnnualReturn2015

(0.07%)

Annual Return 2016

rr_AnnualReturn2016

7.35%

Annual Return 2017

rr_AnnualReturn2017

20.76%

Annual Return 2018

rr_AnnualReturn2018

(8.22%)

1 Year

rr_AverageAnnualReturnYear01

(8.22%)

5 Years

rr_AverageAnnualReturnYear05

4.42%

10 Years

rr_AverageAnnualReturnYear10

9.91%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2035 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(9.65%)

5 Years

rr_AverageAnnualReturnYear05

2.87%

10 Years

rr_AverageAnnualReturnYear10

8.68%

TIAA-CREF Lifecycle 2035 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.01%)

5 Years

rr_AverageAnnualReturnYear05

3.19%

10 Years

rr_AverageAnnualReturnYear10

7.93%

[1] As of the close of business on December 31, 2018, the Lifecycle 2035 Fund Composite Index consisted of: 53.5% Russell 3000® Index; 23.6% Bloomberg Barclays U.S. Aggregate Bond Index; and 22.9% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

TIAA-CREF Lifecycle Index 2020 Fund

TIAA-CREF Lifecycle Index 2020 Fund

Investment objective

The Lifecycle Index 2020 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2020 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2020 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.18%	0.18%	0.18%	0.18%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Total annual Fund operating expenses		0.21%	0.29%	0.36%	0.46%
Waivers and expense reimbursements	[3],[4]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2020 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	56	82	105	137
5 years	107	152	191	247
10 years	$ 257	$ 357	$ 445	$ 569

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2020 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 50.00% of the Fund’s assets to equity Underlying Funds and 50.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2020 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2050. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 35.00%; International Equity: 15.00%; Fixed-Income: 38.00%; Short-Term Fixed-Income: 6.00%; and Inflation-Protected Assets: 6.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	52.40%	U.S. Equity	36.75%	ŸEquity Index Fund	36.75%
		International Equity	15.65%	ŸInternational Equity Index Fund	11.22%
				ŸEmerging Markets Equity Index Fund	4.43%
Fixed-Income	47.60%	Fixed-Income	36.62%	ŸBond Index Fund	36.62%
		Short-Term Fixed-Income	5.48%	ŸShort-Term Bond Index Fund	5.48%
		Inflation- Protected Assets	5.50%	ŸInflation-Linked Bond Fund	5.50%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2020 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 11.35%.

Best quarter: 9.39%, for the quarter ended September 30, 2010. Worst quarter: -9.69%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2020 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(3.97%)	4.16%		6.86%		Sep. 30, 2009
Institutional Class		(3.75%)	4.41%		7.12%		Sep. 30, 2009
Advisor Class		(3.86%)	4.27%	[1]	6.92%	[1]	Dec. 04, 2015
Premier Class		(3.92%)	4.25%		6.96%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(4.74%)	3.47%		6.26%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.11%)	3.03%		5.35%
S&P Target Date 2020 Index		(4.16%)	4.10%		6.82%	[2]
Lifecycle Index 2020 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(3.83%)	4.48%		7.25%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.089% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.011% of average daily net assets for Institutional Class shares; (ii) 0.161% of average daily net assets for Advisor Class shares; (iii) 0.161% of average daily net assets for Premier Class shares; and (iv) 0.261% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI EAFE + Emerging Markets Index; 5.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2045 Fund

TIAA-CREF Lifecycle 2045 Fund

Investment objective

The Lifecycle 2045 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2045 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2045 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.50%	0.50%	0.50%	0.50%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.56%	0.64%	0.71%	0.81%
Waivers and expense reimbursements	[4],[5]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.45%	0.53%	0.60%	0.70%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2045 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 46	$ 54	$ 61	$ 72
3 years	147	172	194	226
5 years	280	324	363	418
10 years	$ 670	$ 767	$ 852	$ 971

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 13% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2045 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 90.00% of the Fund’s assets to equity Underlying Funds, 5.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2045 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2075. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.00%; International Equity: 27.00%; Fixed-Income: 5.00%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	90.42%	U.S. Equity	63.40%	ŸGrowth & Income Fund	13.30%
				ŸLarge-Cap Growth Fund	12.00%
				ŸLarge-Cap Value Fund	11.62%
				ŸQuant Large-Cap Growth Fund	10.48%
				ŸQuant Large-Cap Value Fund	10.19%
				ŸQuant Small-Cap Equity Fund	3.26%
				ŸQuant Small/Mid-Cap Equity Fund	2.55%
		International Equity	27.02%	ŸQuant International Equity Fund	7.05%
				ŸInternational Equity Fund	5.88%
				ŸInternational Opportunities Fund	5.86%
				ŸEmerging Markets Equity Fund	4.63%
				ŸQuant International Small-Cap Equity Fund	3.60%
Fixed-Income	4.97%	Fixed-Income	4.97%	ŸBond Fund	2.60%
				ŸBond Plus Fund	1.61%
				ŸEmerging Markets Debt Fund	0.43%
				ŸInternational Bond Fund	0.26%
				ŸHigh-Yield Fund	0.07%
Real Estate	4.61%	Direct Real Estate	4.61%	ŸTIAA-CREF Real Property Fund LP	4.61%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2045 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.14%.

Best quarter: 17.33%, for the quarter ended June 30, 2009. Worst quarter: -16.44%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2045 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(9.90%)	4.53%		10.10%		Nov. 30, 2007
Institutional Class		(9.59%)	4.81%		10.38%		Nov. 30, 2007
Advisor Class		(9.67%)	4.68%	[1]	10.18%	[1]	Dec. 04, 2015
Premier Class		(9.78%)	4.65%		10.21%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(11.05%)	3.29%		9.12%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(5.20%)	3.30%		8.11%
S&P Target Date 2045 Index		(7.74%)	4.91%		9.88%
Lifecycle 2045 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(7.27%)	5.53%		10.49%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI All Country World Index ex USA Investable Market Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2040 Fund

TIAA-CREF Lifecycle Index 2040 Fund

Investment objective

The Lifecycle Index 2040 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2040 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2040 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.16%	0.16%	0.16%	0.16%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Total annual Fund operating expenses		0.19%	0.27%	0.34%	0.44%
Waivers and expense reimbursements	[3],[4]	(0.09%)	(0.09%)	(0.09%)	(0.09%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2040 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	52	78	100	132
5 years	98	143	182	237
10 years	$ 234	$ 334	$ 422	$ 546

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 6% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2040 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 82.00% of the Fund’s assets to equity Underlying Funds and 18.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2040 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2070. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 57.40%; International Equity: 24.60%; Fixed-Income: 18.00%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	84.01%	U.S. Equity	58.92%	ŸEquity Index Fund	58.92%
		International Equity	25.09%	ŸInternational Equity Index Fund	17.99%
				ŸEmerging Markets Equity Index Fund	7.10%
Fixed-Income	15.99%	Fixed-Income	15.99%	ŸBond Index Fund	15.99%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2040 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.08%.

Best quarter: 11.87%, for the quarter ended September 30, 2010. Worst quarter: -14.82%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2040 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(6.60%)	5.18%		8.68%		Sep. 30, 2009
Institutional Class		(6.36%)	5.45%		8.95%		Sep. 30, 2009
Advisor Class		(6.42%)	5.31%	[1]	8.75%	[1]	Dec. 04, 2015
Premier Class		(6.53%)	5.29%		8.78%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(7.17%)	4.56%		8.15%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.58%)	3.94%		6.98%
S&P Target Date 2040 Index		(7.41%)	4.82%		8.31%	[2]
Lifecycle Index 2040 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(6.50%)	5.51%		9.06%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.065% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.035% of average daily net assets for Institutional Class shares; (ii) 0.185% of average daily net assets for Advisor Class shares; (iii) 0.185% of average daily net assets for Premier Class shares; and (iv) 0.285% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI EAFE + Emerging Markets Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index Retirement Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index Retirement Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index Retirement Income Fund seeks high total return over time primarily through income,

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

with a secondary emphasis on capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

23.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy that will not gradually adjust over time and is designed for investors who are already in retirement (i.e., have already passed their retirement year) and may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets in Underlying Funds that are managed to seek investment returns that track particular market indices. For purposes of the 80% investment policy, the term “assets” means net assets, plus the amount of any borrowings for investment purposes.

Advisors currently expects to allocate approximately 40% of the Fund’s assets to equity Underlying Funds and 60% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations may be changed and actual allocations may vary up to ten percentage points from the targets. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which may change, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; and Inflation-Protected Assets: 10.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income) and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change. Investors should note that the Fund has a significant level of equity exposure and this exposure could cause fluctuation in the value of the Fund depending on the performance of the equity markets generally.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. The Fund has relatively fixed asset allocations that will not gradually adjust over time. Underlying Fund allocations may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	40.69%	U.S. Equity	28.54%	ŸEquity Index Fund	28.54%
		International Equity	12.15%	ŸInternational Equity Index Fund	8.71%
				ŸEmerging Markets Equity Index Fund	3.44%
Fixed-Income	59.31%	Fixed-Income	39.57%	ŸBond Index Fund	39.57%
		Short-Term Fixed-Income	9.85%	ŸShort-Term Bond Index Fund	9.85%
		Inflation- Protected Assets	9.89%	ŸInflation-Linked Bond Fund	9.89%

Total 100.00% 100.00% 100.00%

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI EAFE + Emerging Markets Index; 10.0% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1–10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index Retirement Income Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 9.85%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 6.74%, for the quarter ended September 30, 2010. Worst quarter: -4.69%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

9.85%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.74%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.69%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index Retirement Income Fund | S&P Target Date Retirement Income Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.54%)

5 Years

rr_AverageAnnualReturnYear05

3.06%

Since Inception

rr_AverageAnnualReturnSinceInception

4.75%

^[1]

TIAA-CREF Lifecycle Index Retirement Income Fund | Lifecycle Index Retirement Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.83%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

3.84%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

5.88%

^[1],[2]

TIAA-CREF Lifecycle Index Retirement Income Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.09%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.28%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

72

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

139

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 338

1 Year

rr_AverageAnnualReturnYear01

(2.65%)

5 Years

rr_AverageAnnualReturnYear05

3.79%

Since Inception

rr_AverageAnnualReturnSinceInception

5.76%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index Retirement Income Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.17%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.36%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

97

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

184

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 438

1 Year

rr_AverageAnnualReturnYear01

(2.67%)

5 Years

rr_AverageAnnualReturnYear05

3.66%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index Retirement Income Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.08%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.42%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

118

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

218

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 513

1 Year

rr_AverageAnnualReturnYear01

(2.80%)

5 Years

rr_AverageAnnualReturnYear05

3.62%

Since Inception

rr_AverageAnnualReturnSinceInception

5.60%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index Retirement Income Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.34%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.53%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

152

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

278

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 648

Annual Return 2010

rr_AnnualReturn2010

9.70%

Annual Return 2011

rr_AnnualReturn2011

4.21%

Annual Return 2012

rr_AnnualReturn2012

9.33%

Annual Return 2013

rr_AnnualReturn2013

8.16%

Annual Return 2014

rr_AnnualReturn2014

5.84%

Annual Return 2015

rr_AnnualReturn2015

(0.25%)

Annual Return 2016

rr_AnnualReturn2016

5.20%

Annual Return 2017

rr_AnnualReturn2017

10.24%

Annual Return 2018

rr_AnnualReturn2018

(2.90%)

1 Year

rr_AverageAnnualReturnYear01

(2.90%)

5 Years

rr_AverageAnnualReturnYear05

3.52%

Since Inception

rr_AverageAnnualReturnSinceInception

5.49%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index Retirement Income Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.74%)

5 Years

rr_AverageAnnualReturnYear05

2.78%

Since Inception

rr_AverageAnnualReturnSinceInception

4.77%

TIAA-CREF Lifecycle Index Retirement Income Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.52%)

5 Years

rr_AverageAnnualReturnYear05

2.47%

Since Inception

rr_AverageAnnualReturnSinceInception

4.12%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI EAFE + Emerging Markets Index; 10.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.102% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

XML

Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	May 31, 2019
Entity Registrant Name	TIAA-CREF FUNDS
Entity Central Index Key	0001084380
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Sep. 26, 2019
Document Effective Date	Oct. 01, 2019
Prospectus Date	Oct. 01, 2019

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Oct. 01, 2019

XML

TIAA-CREF Lifestyle Conservative Fund

TIAA-CREF Lifestyle Conservative Fund

Investment objective

The Fund seeks long-term total return, consisting of current income and capital appreciation.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifestyle Conservative Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifestyle Conservative Fund		Institutional Class	Advisor Class		Premier Class	Retirement Class	Retail Class
Management fees		0.10%	0.10%		0.10%	0.10%	0.10%
Distribution (Rule 12b-1) fees					0.15%		0.25%
Other expenses		0.10%	0.17%	[1]	0.10%	0.34%	0.11%
Acquired Fund fees and expenses	[2]	0.36%	0.36%		0.36%	0.36%	0.36%
Total annual Fund operating expenses		0.56%	0.63%		0.71%	0.80%	0.82%
Waivers and expense reimbursements	[3]	(0.10%)	(0.09%)		(0.10%)	(0.09%)	(0.09%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.46%	0.54%		0.61%	0.71%	0.73%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifestyle Conservative Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 47	$ 55	$ 62	$ 73	$ 75
3 years	169	193	217	246	253
5 years	303	342	385	435	446
10 years	$ 692	$ 778	$ 873	$ 981	$ 1,005

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 24% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term total return, consisting of current income and capital appreciation, through a relatively stable asset allocation strategy targeting a conservative risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 40% of the Fund’s assets in equity Underlying Funds and (2) approximately 60% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	40.70%	U.S. Equity	29.53%	ŸLarge-Cap Growth Fund	7.20%
				ŸLarge-Cap Value Fund	6.97%
				ŸGrowth & Income Fund	6.39%
				ŸQuant Large-Cap Growth Fund	4.70%
				ŸQuant Large-Cap Value Fund	1.61%
				ŸQuant Small-Cap Equity Fund	1.43%
				ŸQuant Small/Mid-Cap Equity Fund	1.23%
		International Equity	11.17%	ŸInternational Equity Fund	3.15%
				ŸInternational Opportunities Fund	2.63%
				ŸEmerging Markets Equity Fund	2.08%
				ŸQuant International Equity Fund	1.69%
				ŸQuant International Small-Cap Equity Fund	1.62%
Fixed-Income	59.30%	Fixed-Income	38.59%	ŸBond Plus Fund	29.69%
				ŸBond Fund	8.90%
		Short-Term Fixed-Income	20.71%	ŸShort-Term Bond Fund	20.71%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Conservative Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.28%.

Best quarter: 6.70%, for the quarter ended March 31, 2012. Worst quarter: -6.13%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifestyle Conservative Fund		1 Year	5 Years		Since Inception		Inception Date
Institutional Class		(4.43%)	3.47%		5.60%		Dec. 09, 2011
Advisor Class		(4.62%)	3.43%	[1]	5.57%	[1]	Dec. 04, 2015
Premier Class		(4.63%)	3.29%		5.43%		Dec. 09, 2011
Retirement Class		(4.75%)	3.20%		5.32%		Dec. 09, 2011
Retail Class		(4.77%)	3.18%		5.29%		Dec. 09, 2011
After Taxes on Distributions | Institutional Class		(5.65%)	2.23%		4.41%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(2.22%)	2.29%		4.01%
Morningstar Moderately Conservative Target Risk Index (reflects no deductions for fees, expenses or taxes)		(2.87%)	3.46%		5.09%	[2]
Lifestyle Conservative Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(2.76%)	3.65%		5.21%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Restated to reflect estimate for the current fiscal year.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

[2] Performance is calculated from the inception date of the Institutional Class.

[3] As of the close of business on December 31, 2018, the Lifestyle Conservative Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 20.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 12.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifestyle Conservative Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifestyle Conservative Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term total return, consisting of current income and capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 24% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

24.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term total return, consisting of current income and capital appreciation, through a relatively stable asset allocation strategy targeting a conservative risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 40% of the Fund’s assets in equity Underlying Funds and (2) approximately 60% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	40.70%	U.S. Equity	29.53%	ŸLarge-Cap Growth Fund	7.20%
				ŸLarge-Cap Value Fund	6.97%
				ŸGrowth & Income Fund	6.39%
				ŸQuant Large-Cap Growth Fund	4.70%
				ŸQuant Large-Cap Value Fund	1.61%
				ŸQuant Small-Cap Equity Fund	1.43%
				ŸQuant Small/Mid-Cap Equity Fund	1.23%
		International Equity	11.17%	ŸInternational Equity Fund	3.15%
				ŸInternational Opportunities Fund	2.63%
				ŸEmerging Markets Equity Fund	2.08%
				ŸQuant International Equity Fund	1.69%
				ŸQuant International Small-Cap Equity Fund	1.62%
Fixed-Income	59.30%	Fixed-Income	38.59%	ŸBond Plus Fund	29.69%
				ŸBond Fund	8.90%
		Short-Term Fixed-Income	20.71%	ŸShort-Term Bond Fund	20.71%

Total 100.00% 100.00% 100.00%

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifestyle Conservative Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 20.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 12.0% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Conservative Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.28%.

Bar Chart Closing [Text Block]

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Best quarter: 6.70%, for the quarter ended March 31, 2012. Worst quarter: -6.13%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.28%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.70%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(6.13%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifestyle Conservative Fund | Morningstar Moderately Conservative Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.87%)

5 Years

rr_AverageAnnualReturnYear05

3.46%

Since Inception

rr_AverageAnnualReturnSinceInception

5.09%

^[1]

TIAA-CREF Lifestyle Conservative Fund | Lifestyle Conservative Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.76%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

3.65%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

5.21%

^[1],[2]

TIAA-CREF Lifestyle Conservative Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.10%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.36%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.56%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.46%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 47

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

169

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

303

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 692

Annual Return 2012

rr_AnnualReturn2012

11.78%

Annual Return 2013

rr_AnnualReturn2013

10.84%

Annual Return 2014

rr_AnnualReturn2014

4.28%

Annual Return 2015

rr_AnnualReturn2015

0.65%

Annual Return 2016

rr_AnnualReturn2016

5.43%

Annual Return 2017

rr_AnnualReturn2017

12.12%

Annual Return 2018

rr_AnnualReturn2018

(4.43%)

1 Year

rr_AverageAnnualReturnYear01

(4.43%)

5 Years

rr_AverageAnnualReturnYear05

3.47%

Since Inception

rr_AverageAnnualReturnSinceInception

5.60%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Conservative Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.65%)

5 Years

rr_AverageAnnualReturnYear05

2.23%

Since Inception

rr_AverageAnnualReturnSinceInception

4.41%

TIAA-CREF Lifestyle Conservative Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.22%)

5 Years

rr_AverageAnnualReturnYear05

2.29%

Since Inception

rr_AverageAnnualReturnSinceInception

4.01%

TIAA-CREF Lifestyle Conservative Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.17%

^[5]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.36%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.63%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.54%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 55

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

193

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

342

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 778

1 Year

rr_AverageAnnualReturnYear01

(4.62%)

5 Years

rr_AverageAnnualReturnYear05

3.43%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifestyle Conservative Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.10%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.36%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.71%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.61%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 62

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

217

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

385

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 873

1 Year

rr_AverageAnnualReturnYear01

(4.63%)

5 Years

rr_AverageAnnualReturnYear05

3.29%

Since Inception

rr_AverageAnnualReturnSinceInception

5.43%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Conservative Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.34%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.36%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.80%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.71%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 73

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

246

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

435

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 981

1 Year

rr_AverageAnnualReturnYear01

(4.75%)

5 Years

rr_AverageAnnualReturnYear05

3.20%

Since Inception

rr_AverageAnnualReturnSinceInception

5.32%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Conservative Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.11%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.36%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.82%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.73%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 75

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

253

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

446

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,005

1 Year

rr_AverageAnnualReturnYear01

(4.77%)

5 Years

rr_AverageAnnualReturnYear05

3.18%

Since Inception

rr_AverageAnnualReturnSinceInception

5.29%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

[1] Performance is calculated from the inception date of the Institutional Class.

[2] As of the close of business on December 31, 2018, the Lifestyle Conservative Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 20.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 12.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[5] Restated to reflect estimate for the current fiscal year.

[6] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

XML

TIAA-CREF Lifecycle 2010 Fund

TIAA-CREF Lifecycle 2010 Fund

Investment objective

The Lifecycle 2010 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2010 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2010 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.42%	0.42%	0.42%	0.42%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.05%	0.13%	0.05%	0.30%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.50%	0.58%	0.65%	0.75%
Waivers and expense reimbursements	[4],[5]	(0.13%)	(0.13%)	(0.13%)	(0.13%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.37%	0.45%	0.52%	0.62%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2010 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 38	$ 46	$ 53	$ 63
3 years	125	151	173	205
5 years	245	289	328	383
10 years	$ 595	$ 693	$ 778	$ 898

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 22% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2010 and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 35.00% of the Fund’s assets to equity Underlying Funds, 60.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2010 (the direct real estate asset class was added in 2017) and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2040. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 24.50%; International Equity: 10.50%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; Inflation-Protected Assets: 10.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	37.05%	U.S. Equity	25.99%	ŸGrowth & Income Fund	5.44%
				ŸLarge-Cap Growth Fund	4.93%
				ŸLarge-Cap Value Fund	4.77%
				ŸQuant Large-Cap Growth Fund	4.29%
				ŸQuant Large-Cap Value Fund	4.18%
				ŸQuant Small-Cap Equity Fund	1.33%
				ŸQuant Small/Mid-Cap Equity Fund	1.05%
		International Equity	11.06%	ŸQuant International Equity Fund	2.89%
				ŸInternational Equity Fund	2.40%
				ŸInternational Opportunities Fund	2.40%
				ŸEmerging Markets Equity Fund	1.90%
				ŸQuant International Small-Cap Equity Fund	1.47%
Fixed-Income	58.27%	Fixed-Income	38.38%	ŸBond Fund	19.68%
				ŸBond Plus Fund	12.82%
				ŸEmerging Markets Debt Fund	2.12%
				ŸInternational Bond Fund	2.05%
				ŸHigh-Yield Fund	1.71%
		Short-Term Fixed-Income	10.43%	ŸShort-Term Bond Fund	10.43%
		Inflation- Protected Assets	9.46%	ŸInflation-Linked Bond Fund	9.46%
Real Estate	4.68%	Direct Real Estate	4.68%	ŸTIAA-CREF Real Property Fund LP	4.68%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2010 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.08%.

Best quarter: 10.87%, for the quarter ended June 30, 2009. Worst quarter: -7.99%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2010 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(4.11%)	3.59%		7.30%		Oct. 15, 2004
Institutional Class		(3.92%)	3.85%		7.56%		Jan. 17, 2007
Advisor Class		(3.94%)	3.73%	[1]	7.37%	[1]	Dec. 04, 2015
Premier Class		(4.09%)	3.68%		7.39%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(5.61%)	2.22%		6.16%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(1.86%)	2.39%		5.53%
S&P Target Date 2010 Index		(3.10%)	3.40%		6.24%
Lifecycle 2010 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(3.05%)	3.90%		7.19%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI All Country World Index ex USA Investable Market Index; 9.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifestyle Moderate Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifestyle Moderate Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Fund seeks long-term total return, consisting of capital appreciation and current income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Portfolio Turnover, Rate

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23.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term total return, consisting of capital appreciation and current income, through a relatively stable asset allocation strategy targeting a moderate risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 60% of the Fund’s assets in equity Underlying Funds and (2) approximately 40% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.66%	U.S. Equity	43.54%	ŸLarge-Cap Growth Fund	10.74%
				ŸLarge-Cap Value Fund	10.40%
				ŸGrowth & Income Fund	9.52%
				ŸQuant Large-Cap Growth Fund	6.02%
				ŸQuant Large-Cap Value Fund	2.90%
				ŸQuant Small-Cap Equity Fund	2.13%
				ŸQuant Small/Mid-Cap Equity Fund	1.83%
		International Equity	17.12%	ŸInternational Equity Fund	4.72%
				ŸInternational Opportunities Fund	3.92%
				ŸEmerging Markets Equity Fund	3.10%
				ŸQuant International Equity Fund	2.97%
				ŸQuant International Small-Cap Equity Fund	2.41%
Fixed-Income	39.34%	Fixed-Income	39.34%	ŸBond Plus Fund	39.34%

Total 100.00% 100.00% 100.00%

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifestyle Moderate Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Moderate Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.34%.

Bar Chart Closing [Text Block]

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Best quarter: 9.36%, for the quarter ended March 31, 2012. Worst quarter: -9.55%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

13.34%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

9.36%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.55%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifestyle Moderate Fund | Morningstar Moderate Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.76%)

5 Years

rr_AverageAnnualReturnYear05

4.08%

Since Inception

rr_AverageAnnualReturnSinceInception

6.57%

^[1]

TIAA-CREF Lifestyle Moderate Fund | Lifestyle Moderate Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.69%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.61%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

7.01%

^[1],[2]

TIAA-CREF Lifestyle Moderate Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.07%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.40%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.57%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

176

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

311

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 707

Annual Return 2012

rr_AnnualReturn2012

15.12%

Annual Return 2013

rr_AnnualReturn2013

16.84%

Annual Return 2014

rr_AnnualReturn2014

4.98%

Annual Return 2015

rr_AnnualReturn2015

0.46%

Annual Return 2016

rr_AnnualReturn2016

6.59%

Annual Return 2017

rr_AnnualReturn2017

17.00%

Annual Return 2018

rr_AnnualReturn2018

(6.95%)

1 Year

rr_AverageAnnualReturnYear01

(6.95%)

5 Years

rr_AverageAnnualReturnYear05

4.12%

Since Inception

rr_AverageAnnualReturnSinceInception

7.28%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Moderate Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(8.19%)

5 Years

rr_AverageAnnualReturnYear05

2.79%

Since Inception

rr_AverageAnnualReturnSinceInception

6.01%

TIAA-CREF Lifestyle Moderate Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.58%)

5 Years

rr_AverageAnnualReturnYear05

2.83%

Since Inception

rr_AverageAnnualReturnSinceInception

5.40%

TIAA-CREF Lifestyle Moderate Fund | Advisor Class

Risk/Return:

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Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.15%

^[5]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.40%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.65%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.58%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 59

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

201

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

355

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 804

1 Year

rr_AverageAnnualReturnYear01

(7.00%)

5 Years

rr_AverageAnnualReturnYear05

4.08%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

7.25%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifestyle Moderate Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.07%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.40%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.72%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.65%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 66

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

223

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

394

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 888

1 Year

rr_AverageAnnualReturnYear01

(7.12%)

5 Years

rr_AverageAnnualReturnYear05

3.99%

Since Inception

rr_AverageAnnualReturnSinceInception

7.13%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Moderate Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.32%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.40%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.82%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.75%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 77

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

255

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

448

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,007

1 Year

rr_AverageAnnualReturnYear01

(7.19%)

5 Years

rr_AverageAnnualReturnYear05

3.87%

Since Inception

rr_AverageAnnualReturnSinceInception

7.02%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Moderate Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.08%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.40%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.83%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.06%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.77%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 79

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

259

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

455

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,020

1 Year

rr_AverageAnnualReturnYear01

(7.28%)

5 Years

rr_AverageAnnualReturnYear05

3.83%

Since Inception

rr_AverageAnnualReturnSinceInception

6.97%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

[1] Performance is calculated from the inception date of the Institutional Class.

[2] As of the close of business on December 31, 2018, the Lifestyle Moderate Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[5] Restated to reflect estimate for the current fiscal year.

[6] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

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TIAA-CREF Lifecycle 2030 Fund

TIAA-CREF Lifecycle 2030 Fund

Investment objective

The Lifecycle 2030 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2030 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2030 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.47%	0.47%	0.47%	0.47%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.03%	0.11%	0.03%	0.28%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.53%	0.61%	0.68%	0.78%
Waivers and expense reimbursements	[4],[5]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.42%	0.50%	0.57%	0.67%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2030 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 43	$ 51	$ 58	$ 68
3 years	137	163	185	217
5 years	264	308	346	401
10 years	$ 634	$ 731	$ 816	$ 936

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2030 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 63.00% of the Fund’s assets to equity Underlying Funds, 32.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2030 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2060. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 44.10%; International Equity: 18.90%; Fixed-Income: 28.00%; Short-Term Fixed-Income: 2.00%; Inflation-Protected Assets 2.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	65.62%	U.S. Equity	46.03%	ŸGrowth & Income Fund	9.64%
				ŸLarge-Cap Growth Fund	8.73%
				ŸLarge-Cap Value Fund	8.44%
				ŸQuant Large-Cap Growth Fund	7.61%
				ŸQuant Large-Cap Value Fund	7.40%
				ŸQuant Small-Cap Equity Fund	2.36%
				ŸQuant Small/Mid-Cap Equity Fund	1.85%
		International Equity	19.59%	ŸQuant International Equity Fund	5.11%
				ŸInternational Equity Fund	4.26%
				ŸInternational Opportunities Fund	4.25%
				ŸEmerging Markets Equity Fund	3.36%
				ŸQuant International Small-Cap Equity Fund	2.61%
Fixed-Income	29.73%	Fixed-Income	25.63%	ŸBond Fund	12.98%
				ŸBond Plus Fund	8.67%
				ŸEmerging Markets Debt Fund	1.51%
				ŸInternational Bond Fund	1.39%
				ŸHigh-Yield Fund	1.08%
		Short-Term Fixed-Income	2.54%	ŸShort-Term Bond Fund	2.54%
		Inflation- Protected Assets	1.56%	ŸInflation-Linked Bond Fund	1.56%
Real Estate	4.65%	Direct Real Estate	4.65%	ŸTIAA-CREF Real Property Fund LP	4.65%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2030 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.54%.

Best quarter: 16.62%, for the quarter ended June 30, 2009. Worst quarter: -14.58%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2030 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(7.24%)	4.30%		9.45%		Oct. 15, 2004
Institutional Class		(7.09%)	4.56%		9.73%		Jan. 17, 2007
Advisor Class		(7.14%)	4.43%	[1]	9.52%	[1]	Dec. 04, 2015
Premier Class		(7.18%)	4.42%		9.55%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(8.73%)	2.73%		8.20%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.45%)	3.06%		7.50%
S&P Target Date 2030 Index		(5.99%)	4.50%		8.96%
Lifecycle 2030 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(5.35%)	4.99%		9.61%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI All Country World Index ex USA Investable Market Index; 1.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifestyle Aggressive Growth Fund

TIAA-CREF Lifestyle Aggressive Growth Fund

Investment objective

The Fund seeks long-term growth of capital.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifestyle Aggressive Growth Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifestyle Aggressive Growth Fund		Institutional Class	Advisor Class		Premier Class	Retirement Class	Retail Class
Management fees		0.10%	0.10%		0.10%	0.10%	0.10%
Distribution (Rule 12b-1) fees					0.15%		0.25%
Other expenses		0.18%	0.25%	[1]	0.18%	0.42%	0.22%
Acquired Fund fees and expenses	[2]	0.46%	0.46%		0.46%	0.46%	0.46%
Total annual Fund operating expenses		0.74%	0.81%		0.89%	0.98%	1.03%
Waivers and expense reimbursements	[3]	(0.18%)	(0.18%)		(0.18%)	(0.17%)	(0.17%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.56%	0.63%		0.71%	0.81%	0.86%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifestyle Aggressive Growth Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 57	$ 64	$ 73	$ 83	$ 88
3 years	218	241	266	295	311
5 years	394	432	475	525	552
10 years	$ 902	$ 985	$ 1,080	$ 1,186	$ 1,244

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 24% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term growth of capital through a relatively stable asset allocation strategy targeting an aggressive growth risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 100% of the Fund’s assets in equity Underlying Funds and (2) approximately 0% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	100.00%	U.S. Equity	71.06%	ŸLarge-Cap Growth Fund	17.67%
				ŸLarge-Cap Value Fund	17.18%
				ŸGrowth & Income Fund	15.68%
				ŸQuant Large-Cap Growth Fund	8.61%
				ŸQuant Large-Cap Value Fund	5.44%
				ŸQuant Small-Cap Equity Fund	3.47%
				ŸQuant Small/Mid-Cap Equity Fund	3.01%
		International Equity	28.94%	ŸInternational Equity Fund	7.80%
				ŸInternational Opportunities Fund	6.50%
				ŸQuant International Equity Fund	5.52%
				ŸEmerging Markets Equity Fund	5.13%
				ŸQuant International Small-Cap Equity Fund	3.99%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a significantly higher percentage of equity Underlying Funds, Equity Underlying Funds Risks are expected to predominate.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Aggressive Growth Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 17.61%.

Best quarter: 14.33%, for the quarter ended March 31, 2012. Worst quarter: -15.89%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifestyle Aggressive Growth Fund		1 Year	5 Years		Since Inception		Inception Date
Institutional Class		(11.18%)	4.69%		9.75%		Dec. 09, 2011
Advisor Class		(11.17%)	4.66%	[1]	9.73%	[1]	Dec. 04, 2015
Premier Class		(11.29%)	4.54%		9.59%		Dec. 09, 2011
Retirement Class		(11.39%)	4.42%		9.47%		Dec. 09, 2011
Retail Class		(11.46%)	4.35%		9.39%		Dec. 09, 2011
After Taxes on Distributions | Institutional Class		(12.33%)	3.37%		8.48%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(5.82%)	3.48%		7.65%
Morningstar Aggressive Target Risk Index (reflects no deductions for fees, expenses or taxes)		(8.17%)	5.01%		9.03%	[2]
Lifestyle Aggressive Growth Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(8.12%)	5.74%		10.06%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Restated to reflect estimate for the current fiscal year.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

[2] Performance is calculated from the inception date of the Institutional Class.

[3] As of the close of business on December 31, 2018, the Lifestyle Aggressive Growth Fund Composite Index consisted of: 70.0% Russell 3000® Index; and 30.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Managed Allocation Fund

TIAA-CREF Managed Allocation Fund

Investment objective

The Fund seeks favorable returns that reflect the broad investment performance of the financial markets through capital appreciation and investment income. The Fund will pursue this goal through a “fund of funds” approach, whereby the Fund will make investments primarily in other mutual funds.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Managed Allocation Fund - USD ($)	Institutional Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none
Maximum deferred sales charge	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none
Redemption or exchange fee	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Managed Allocation Fund		Institutional Class	Retirement Class	Retail Class
Distribution (Rule 12b-1) fees				0.25%
Other expenses		0.03%	0.28%	0.07%
Acquired Fund fees and expenses	[1]	0.39%	0.39%	0.39%
Total annual Fund operating expenses		0.42%	0.67%	0.71%
Waivers and expense reimbursements	[2]	(0.03%)	(0.03%)	(0.07%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.39%	0.64%	0.64%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Managed Allocation Fund - USD ($)	Institutional Class	Retirement Class	Retail Class
1 year	$ 40	$ 65	$ 65
3 years	132	211	220
5 years	232	370	388
10 years	$ 527	$ 832	$ 876

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy and will generally seek to meet its investment objective by investing: (1) approximately 60.00% of its assets in equity Underlying Funds, including up to 5.00% of its assets in real estate Underlying Funds; and (2) approximately 40.00% of its assets in fixed-income Underlying Funds (“target allocations”).

The Fund may invest in the following equity Underlying Funds: TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant International Equity Fund, Quant International Small-Cap Equity Fund, Quant Small-Cap Equity Fund, Quant Small/Mid-Cap Equity Fund, Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund and Real Estate Securities Fund.

The Fund may invest in the following fixed-income Underlying Funds: TIAA-CREF Bond Plus Fund, High-Yield Fund, Inflation-Linked Bond Fund, International Bond Fund, Money Market Fund and Short-Term Bond Fund.

As a result of its investments in the Underlying Funds, the Managed Allocation Fund’s returns will reflect investments in a mix of domestic stocks of companies of all sizes, foreign equities, real estate securities and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the foreign and domestic equity markets, as well as overall financial and economic conditions. If the portfolio managers believe that the relative attractiveness of the markets in which the equity and fixed-income funds are invested changes, they can adjust the percentage of investments in the Fund’s market sectors or Underlying Funds up or down by up to 10%; they may also invest in new market sectors or Underlying Funds without prior notice. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above or in the chart below, shareholders will receive prior notice of such change. At any given time the Fund may hold between 0% to 5% of its assets in real estate funds. The

Fund’s composite benchmark is a composite of three benchmark indices representing three types of market sectors within the equity and fixed-income Underlying Fund asset classes, i.e., domestic equity, international equity and fixed-income. The composite index is created by applying the results of the benchmark for each of these three market sectors in proportion to the Fund’s target allocations among the three market sectors. For more information about the different indices that comprise the Fund’s composite benchmark index, please see “Additional information about the Fund’s composite index” below.

The composition of the Fund’s fixed-income portion will vary depending on the shape of the yield curve. This means that when there is not much difference between the yield on short-term and long-term bonds, the Fund would normally increase its investments in the Short-Term Bond Fund. The Fund will have less than 5% of its assets in the High-Yield Fund.

The Fund might sometimes be even more heavily weighted toward equities or fixed-income, if Advisors believes market conditions warrant. For example, the Fund might increase its holdings in fixed-income funds in periods when Advisors believes equity markets will decline.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Board has authorized the Fund to invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”). The Fund may use investments in ETFs and ETNs to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

For flexibility in meeting redemptions, expenses and the timing of new investments, and as a short-term defense during periods of unusual volatility, the Fund may invest in government securities (as defined in the Investment Company Act of 1940, as amended (the “1940 Act”)), short-term paper or shares of the Money Market Fund. For temporary defensive purposes, the Managed Allocation Fund may invest without limitation in such securities. The Fund cannot guarantee that this strategy will be successful.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.65%	U.S. Equity	43.54%	ŸQuant Large-Cap Growth Fund	8.99%
				ŸGrowth & Income Fund	8.93%
				ŸLarge-Cap Growth Fund	8.07%
				ŸLarge-Cap Value Fund	7.81%
				ŸQuant Large-Cap Value Fund	5.84%
				ŸQuant Small-Cap Equity Fund	2.19%
				ŸQuant Small/Mid-Cap Equity Fund	1.71%
		International Equity	17.11%	ŸInternational Equity Fund	3.93%
				ŸInternational Opportunities Fund	3.93%
				ŸQuant International Equity Fund	3.74%
				ŸEmerging Markets Equity Fund	3.10%
				ŸQuant International Small-Cap Equity Fund	2.41%
Fixed-Income	39.35%	Fixed-Income	39.35%	ŸBond Plus Fund	39.35%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. Accordingly, an investment in the Fund or the Underlying Funds typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)†

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.22%.

Best quarter: 12.65%, for the quarter ended June 30, 2009. Worst quarter: -10.49%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Managed Allocation Fund		1 Year	5 Years	10 Years	Inception Date
Institutional Class		(6.82%)	4.29%	8.71%	Mar. 31, 2006
Retirement Class		(6.99%)	4.03%	8.43%	Mar. 31, 2006
Retail Class		(6.96%)	4.03%	8.47%	Mar. 31, 2006
After Taxes on Distributions | Institutional Class		(8.36%)	2.62%	7.34%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(3.32%)	2.92%	6.68%
Morningstar Moderate Target Risk Index (reflects no deductions for fees, expenses or taxes)		(4.76%)	4.08%	7.97%
Managed Allocation Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[1]	(4.69%)	4.61%	8.29%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[2] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Retirement Class shares; and (iii) 0.25% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] As of the close of business on December 31, 2018, the Managed Allocation Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2060 Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifecycle 2060 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle 2060 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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Sep. 30, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal period ended May 31, 2019, the Fund’s portfolio turnover rate was 36% of the average value of its portfolio.

Portfolio Turnover, Rate

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36.00%

Expenses Restated to Reflect Current [Text]

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Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2060 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 93.75% of the Fund’s assets to equity Underlying Funds, 1.25% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2060 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2090. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 65.62%; International Equity: 28.13%; Fixed-Income: 1.25%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, for June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	94.11%	U.S. Equity	65.99%	ŸGrowth & Income Fund	13.84%
				ŸLarge-Cap Growth Fund	12.49%
				ŸLarge-Cap Value Fund	12.10%
				ŸQuant Large-Cap Growth Fund	10.91%
				ŸQuant Large-Cap Value Fund	10.60%
				ŸQuant Small-Cap Equity Fund	3.39%
				ŸQuant Small/Mid-Cap Equity Fund	2.66%
		International Equity	28.12%	ŸQuant International Equity Fund	7.34%
				ŸInternational Equity Fund	6.12%
				ŸInternational Opportunities Fund	6.10%
				ŸEmerging Markets Equity Fund	4.81%
				ŸQuant International Small-Cap Equity Fund	3.75%
Fixed-Income	1.32%	Fixed-Income	1.32%	ŸBond Fund	0.69%
				ŸBond Plus Fund	0.42%
				ŸHigh-Yield Fund	0.07%
				ŸInternational Bond Fund	0.07%
				ŸEmerging Markets Debt Fund	0.07%
Real Estate	4.57%	Direct Real Estate	4.57%	ŸTIAA-CREF Real Property Fund LP	4.57%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifecycle 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI All Country World Index ex USA Investable Market Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2060 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.49%.

Bar Chart Closing [Text Block]

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Best quarter: 6.77%, for the quarter ended March 31, 2017. Worst quarter: -14.70%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.49%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.77%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.70%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2060 Fund | S&P Target Date 2060+ Index

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

(7.95%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.99%

^[1]

TIAA-CREF Lifecycle 2060 Fund | Lifecycle 2060 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.59%)

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

5.40%

^[1],[2]

TIAA-CREF Lifecycle 2060 Fund | Institutional Class

Risk/Return:

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Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.18%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.71%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

179

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

348

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 838

1 Year

rr_AverageAnnualReturnYear01

(10.06%)

Since Inception

rr_AverageAnnualReturnSinceInception

5.01%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle 2060 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.26%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.79%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

205

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

392

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 933

1 Year

rr_AverageAnnualReturnYear01

(10.16%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.93%

^[8]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2060 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.18%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.86%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.60%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 61

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

227

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

430

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,017

1 Year

rr_AverageAnnualReturnYear01

(10.27%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle 2060 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.43%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.96%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.26%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

258

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

484

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,134

Annual Return 2015

rr_AnnualReturn2015

(0.03%)

Annual Return 2016

rr_AnnualReturn2016

8.09%

Annual Return 2017

rr_AnnualReturn2017

24.21%

Annual Return 2018

rr_AnnualReturn2018

(10.28%)

1 Year

rr_AverageAnnualReturnYear01

(10.28%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.78%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle 2060 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(11.24%)

Since Inception

rr_AverageAnnualReturnSinceInception

3.56%

TIAA-CREF Lifecycle 2060 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.50%)

Since Inception

rr_AverageAnnualReturnSinceInception

3.49%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI All Country World Index ex USA Investable Market Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[6] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[7] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[8] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.Performance is calculated from the inception date of the Retirement Class.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2050 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2050 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2050 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

12.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2050 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 91.25% of the Fund’s assets to equity Underlying Funds, 3.75% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2050 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2080. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.87%; International Equity: 27.38%; Fixed-Income: 3.75%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	91.63%	U.S. Equity	64.24%	ŸGrowth & Income Fund	13.47%
				ŸLarge-Cap Growth Fund	12.15%
				ŸLarge-Cap Value Fund	11.78%
				ŸQuant Large-Cap Growth Fund	10.63%
				ŸQuant Large-Cap Value Fund	10.32%
				ŸQuant Small-Cap Equity Fund	3.30%
				ŸQuant Small/Mid-Cap Equity Fund	2.59%
		International Equity	27.39%	ŸQuant International Equity Fund	7.15%
				ŸInternational Equity Fund	5.96%
				ŸInternational Opportunities Fund	5.94%
				ŸEmerging Markets Equity Fund	4.69%
				ŸQuant International Small-Cap Equity Fund	3.65%
Fixed-Income	3.76%	Fixed-Income	3.76%	ŸBond Fund	1.97%
				ŸBond Plus Fund	1.22%
				ŸEmerging Markets Debt Fund	0.31%
				ŸInternational Bond Fund	0.20%
				ŸHigh-Yield Fund	0.06%
Real Estate	4.61%	Direct Real Estate	4.61%	ŸTIAA-CREF Real Property Fund LP	4.61%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI All Country World Index ex USA Investable Market Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2050 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.25%.

Bar Chart Closing [Text Block]

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Best quarter: 17.30%, for the quarter ended June 30, 2009. Worst quarter: -16.40%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.30%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.40%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2050 Fund | S&P Target Date 2050 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.94%)

5 Years

rr_AverageAnnualReturnYear05

5.01%

10 Years

rr_AverageAnnualReturnYear10

10.02%

TIAA-CREF Lifecycle 2050 Fund | Lifecycle 2050 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.38%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

5.59%

^[1]

10 Years

rr_AverageAnnualReturnYear10

10.52%

^[1]

TIAA-CREF Lifecycle 2050 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.57%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

149

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

285

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 681

1 Year

rr_AverageAnnualReturnYear01

(9.82%)

5 Years

rr_AverageAnnualReturnYear05

4.85%

10 Years

rr_AverageAnnualReturnYear10

10.37%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle 2050 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.65%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

174

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

329

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 779

1 Year

rr_AverageAnnualReturnYear01

(9.83%)

5 Years

rr_AverageAnnualReturnYear05

4.72%

^[7]

10 Years

rr_AverageAnnualReturnYear10

10.17%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2050 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.72%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.60%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 61

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

197

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

367

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 863

1 Year

rr_AverageAnnualReturnYear01

(9.93%)

5 Years

rr_AverageAnnualReturnYear05

4.70%

10 Years

rr_AverageAnnualReturnYear10

10.20%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2050 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.82%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

228

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

422

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 982

Annual Return 2009

rr_AnnualReturn2009

28.05%

Annual Return 2010

rr_AnnualReturn2010

15.03%

Annual Return 2011

rr_AnnualReturn2011

(3.80%)

Annual Return 2012

rr_AnnualReturn2012

17.24%

Annual Return 2013

rr_AnnualReturn2013

25.98%

Annual Return 2014

rr_AnnualReturn2014

4.26%

Annual Return 2015

rr_AnnualReturn2015

(0.06%)

Annual Return 2016

rr_AnnualReturn2016

7.91%

Annual Return 2017

rr_AnnualReturn2017

23.62%

Annual Return 2018

rr_AnnualReturn2018

(9.98%)

1 Year

rr_AverageAnnualReturnYear01

(9.98%)

5 Years

rr_AverageAnnualReturnYear05

4.59%

10 Years

rr_AverageAnnualReturnYear10

10.11%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle 2050 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(11.10%)

5 Years

rr_AverageAnnualReturnYear05

3.37%

10 Years

rr_AverageAnnualReturnYear10

9.13%

TIAA-CREF Lifecycle 2050 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.25%)

5 Years

rr_AverageAnnualReturnYear05

3.35%

10 Years

rr_AverageAnnualReturnYear10

8.13%

[1] As of the close of business on December 31, 2018, the Lifecycle 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI All Country World Index ex USA Investable Market Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

TIAA-CREF Lifecycle 2060 Fund

TIAA-CREF Lifecycle 2060 Fund

Investment objective

The Lifecycle 2060 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2060 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2060 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.50%	0.50%	0.50%	0.50%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.18%	0.26%	0.18%	0.43%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.71%	0.79%	0.86%	0.96%
Waivers and expense reimbursements	[4],[5]	(0.26%)	(0.26%)	(0.26%)	(0.26%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.45%	0.53%	0.60%	0.70%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2060 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 46	$ 54	$ 61	$ 72
3 years	179	205	227	258
5 years	348	392	430	484
10 years	$ 838	$ 933	$ 1,017	$ 1,134

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal period ended May 31, 2019, the Fund’s portfolio turnover rate was 36% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2060 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 93.75% of the Fund’s assets to equity Underlying Funds, 1.25% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2060 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2090. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 65.62%; International Equity: 28.13%; Fixed-Income: 1.25%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, for June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	94.11%	U.S. Equity	65.99%	ŸGrowth & Income Fund	13.84%
				ŸLarge-Cap Growth Fund	12.49%
				ŸLarge-Cap Value Fund	12.10%
				ŸQuant Large-Cap Growth Fund	10.91%
				ŸQuant Large-Cap Value Fund	10.60%
				ŸQuant Small-Cap Equity Fund	3.39%
				ŸQuant Small/Mid-Cap Equity Fund	2.66%
		International Equity	28.12%	ŸQuant International Equity Fund	7.34%
				ŸInternational Equity Fund	6.12%
				ŸInternational Opportunities Fund	6.10%
				ŸEmerging Markets Equity Fund	4.81%
				ŸQuant International Small-Cap Equity Fund	3.75%
Fixed-Income	1.32%	Fixed-Income	1.32%	ŸBond Fund	0.69%
				ŸBond Plus Fund	0.42%
				ŸHigh-Yield Fund	0.07%
				ŸInternational Bond Fund	0.07%
				ŸEmerging Markets Debt Fund	0.07%
Real Estate	4.57%	Direct Real Estate	4.57%	ŸTIAA-CREF Real Property Fund LP	4.57%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2060 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.49%.

Best quarter: 6.77%, for the quarter ended March 31, 2017. Worst quarter: -14.70%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2060 Fund		1 Year	Since Inception		Inception Date
Retirement Class		(10.28%)	4.78%		Sep. 26, 2014
Institutional Class		(10.06%)	5.01%		Sep. 26, 2014
Advisor Class		(10.16%)	4.93%	[1]	Dec. 04, 2015
Premier Class		(10.27%)	4.86%		Sep. 26, 2014
After Taxes on Distributions | Retirement Class		(11.24%)	3.56%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(5.50%)	3.49%
S&P Target Date 2060+ Index		(7.95%)	4.99%	[2]
Lifecycle 2060 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.59%)	5.40%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.Performance is calculated from the inception date of the Retirement Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI All Country World Index ex USA Investable Market Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2025 Fund

TIAA-CREF Lifecycle Index 2025 Fund

Investment objective

The Lifecycle Index 2025 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2025 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2025 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.17%	0.17%	0.17%	0.17%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.14%	0.04%	0.29%
Total annual Fund operating expenses		0.21%	0.31%	0.36%	0.46%
Waivers and expense reimbursements	[3],[4]	(0.11%)	(0.11%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.20%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2025 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 20	$ 26	$ 36
3 years	56	89	105	137
5 years	107	163	191	247
10 years	$ 257	$ 382	$ 445	$ 569

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 11% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2025 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 58.00% of the Fund’s assets to equity Underlying Funds and 42.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2025 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2055. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 40.60%; International Equity: 17.40%; Fixed-Income: 34.00%; Short-Term Fixed-Income: 4.00%; and Inflation-Protected Assets: 4.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.34%	U.S. Equity	42.32%	ŸEquity Index Fund	42.32%
		International Equity	18.02%	ŸInternational Equity Index Fund	12.92%
				ŸEmerging Markets Equity Index Fund	5.10%
Fixed-Income	39.66%	Fixed-Income	32.62%	ŸBond Index Fund	32.62%
		Short-Term Fixed-Income	3.51%	ŸShort-Term Bond Index Fund	3.51%
		Inflation- Protected Assets	3.53%	ŸInflation-Linked Bond Fund	3.53%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2025 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 12.34%.

Best quarter: 10.18%, for the quarter ended September 30, 2010. Worst quarter: -11.34%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2025 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(4.65%)	4.44%		7.38%		Sep. 30, 2009
Institutional Class		(4.42%)	4.70%		7.65%		Sep. 30, 2009
Advisor Class		(4.49%)	4.56%	[1]	7.45%	[1]	Dec. 04, 2015
Premier Class		(4.58%)	4.53%		7.49%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(5.34%)	3.78%		6.81%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.51%)	3.28%		5.82%
S&P Target Date 2025 Index		(5.02%)	4.31%		7.31%	[2]
Lifecycle Index 2025 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(4.49%)	4.77%		7.77%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.082% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.018% of average daily net assets for Institutional Class shares; (ii) 0.168% of average daily net assets for Advisor Class shares; (iii) 0.168% of average daily net assets for Premier Class shares; and (iv) 0.268% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI EAFE + Emerging Markets Index; 3.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2030 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2030 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle 2030 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

20.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2030 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 63.00% of the Fund’s assets to equity Underlying Funds, 32.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2030 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2060. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 44.10%; International Equity: 18.90%; Fixed-Income: 28.00%; Short-Term Fixed-Income: 2.00%; Inflation-Protected Assets 2.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	65.62%	U.S. Equity	46.03%	ŸGrowth & Income Fund	9.64%
				ŸLarge-Cap Growth Fund	8.73%
				ŸLarge-Cap Value Fund	8.44%
				ŸQuant Large-Cap Growth Fund	7.61%
				ŸQuant Large-Cap Value Fund	7.40%
				ŸQuant Small-Cap Equity Fund	2.36%
				ŸQuant Small/Mid-Cap Equity Fund	1.85%
		International Equity	19.59%	ŸQuant International Equity Fund	5.11%
				ŸInternational Equity Fund	4.26%
				ŸInternational Opportunities Fund	4.25%
				ŸEmerging Markets Equity Fund	3.36%
				ŸQuant International Small-Cap Equity Fund	2.61%
Fixed-Income	29.73%	Fixed-Income	25.63%	ŸBond Fund	12.98%
				ŸBond Plus Fund	8.67%
				ŸEmerging Markets Debt Fund	1.51%
				ŸInternational Bond Fund	1.39%
				ŸHigh-Yield Fund	1.08%
		Short-Term Fixed-Income	2.54%	ŸShort-Term Bond Fund	2.54%
		Inflation- Protected Assets	1.56%	ŸInflation-Linked Bond Fund	1.56%
Real Estate	4.65%	Direct Real Estate	4.65%	ŸTIAA-CREF Real Property Fund LP	4.65%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI All Country World Index ex USA Investable Market Index; 1.4% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2030 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.54%.

Bar Chart Closing [Text Block]

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Best quarter: 16.62%, for the quarter ended June 30, 2009. Worst quarter: -14.58%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

13.54%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

16.62%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.58%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2030 Fund | S&P Target Date 2030 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.99%)

5 Years

rr_AverageAnnualReturnYear05

4.50%

10 Years

rr_AverageAnnualReturnYear10

8.96%

TIAA-CREF Lifecycle 2030 Fund | Lifecycle 2030 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.35%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

4.99%

^[1]

10 Years

rr_AverageAnnualReturnYear10

9.61%

^[1]

TIAA-CREF Lifecycle 2030 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.47%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.53%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.42%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 43

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

137

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

264

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 634

1 Year

rr_AverageAnnualReturnYear01

(7.09%)

5 Years

rr_AverageAnnualReturnYear05

4.56%

10 Years

rr_AverageAnnualReturnYear10

9.73%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2030 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.47%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.61%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

163

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

308

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 731

1 Year

rr_AverageAnnualReturnYear01

(7.14%)

5 Years

rr_AverageAnnualReturnYear05

4.43%

^[7]

10 Years

rr_AverageAnnualReturnYear10

9.52%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2030 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.47%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.68%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.57%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 58

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

185

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

346

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 816

1 Year

rr_AverageAnnualReturnYear01

(7.18%)

5 Years

rr_AverageAnnualReturnYear05

4.42%

10 Years

rr_AverageAnnualReturnYear10

9.55%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2030 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.47%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.78%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.67%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 68

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

217

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

401

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 936

Annual Return 2009

rr_AnnualReturn2009

26.70%

Annual Return 2010

rr_AnnualReturn2010

14.39%

Annual Return 2011

rr_AnnualReturn2011

(2.61%)

Annual Return 2012

rr_AnnualReturn2012

16.21%

Annual Return 2013

rr_AnnualReturn2013

21.84%

Annual Return 2014

rr_AnnualReturn2014

4.53%

Annual Return 2015

rr_AnnualReturn2015

0.05%

Annual Return 2016

rr_AnnualReturn2016

7.07%

Annual Return 2017

rr_AnnualReturn2017

18.86%

Annual Return 2018

rr_AnnualReturn2018

(7.24%)

1 Year

rr_AverageAnnualReturnYear01

(7.24%)

5 Years

rr_AverageAnnualReturnYear05

4.30%

10 Years

rr_AverageAnnualReturnYear10

9.45%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2030 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(8.73%)

5 Years

rr_AverageAnnualReturnYear05

2.73%

10 Years

rr_AverageAnnualReturnYear10

8.20%

TIAA-CREF Lifecycle 2030 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.45%)

5 Years

rr_AverageAnnualReturnYear05

3.06%

10 Years

rr_AverageAnnualReturnYear10

7.50%

[1] As of the close of business on December 31, 2018, the Lifecycle 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI All Country World Index ex USA Investable Market Index; 1.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2045 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2045 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2045 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 13% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

13.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2045 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 90.00% of the Fund’s assets to equity Underlying Funds, 5.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2045 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2075. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.00%; International Equity: 27.00%; Fixed-Income: 5.00%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	90.42%	U.S. Equity	63.40%	ŸGrowth & Income Fund	13.30%
				ŸLarge-Cap Growth Fund	12.00%
				ŸLarge-Cap Value Fund	11.62%
				ŸQuant Large-Cap Growth Fund	10.48%
				ŸQuant Large-Cap Value Fund	10.19%
				ŸQuant Small-Cap Equity Fund	3.26%
				ŸQuant Small/Mid-Cap Equity Fund	2.55%
		International Equity	27.02%	ŸQuant International Equity Fund	7.05%
				ŸInternational Equity Fund	5.88%
				ŸInternational Opportunities Fund	5.86%
				ŸEmerging Markets Equity Fund	4.63%
				ŸQuant International Small-Cap Equity Fund	3.60%
Fixed-Income	4.97%	Fixed-Income	4.97%	ŸBond Fund	2.60%
				ŸBond Plus Fund	1.61%
				ŸEmerging Markets Debt Fund	0.43%
				ŸInternational Bond Fund	0.26%
				ŸHigh-Yield Fund	0.07%
Real Estate	4.61%	Direct Real Estate	4.61%	ŸTIAA-CREF Real Property Fund LP	4.61%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI All Country World Index ex USA Investable Market Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2045 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.14%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 17.33%, for the quarter ended June 30, 2009. Worst quarter: -16.44%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.14%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.33%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.44%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2045 Fund | S&P Target Date 2045 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.74%)

5 Years

rr_AverageAnnualReturnYear05

4.91%

10 Years

rr_AverageAnnualReturnYear10

9.88%

TIAA-CREF Lifecycle 2045 Fund | Lifecycle 2045 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.27%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

5.53%

^[1]

10 Years

rr_AverageAnnualReturnYear10

10.49%

^[1]

TIAA-CREF Lifecycle 2045 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.56%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

147

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

280

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 670

1 Year

rr_AverageAnnualReturnYear01

(9.59%)

5 Years

rr_AverageAnnualReturnYear05

4.81%

10 Years

rr_AverageAnnualReturnYear10

10.38%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle 2045 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.64%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

172

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

324

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 767

1 Year

rr_AverageAnnualReturnYear01

(9.67%)

5 Years

rr_AverageAnnualReturnYear05

4.68%

^[7]

10 Years

rr_AverageAnnualReturnYear10

10.18%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2045 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.71%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.60%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 61

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

194

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

363

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 852

1 Year

rr_AverageAnnualReturnYear01

(9.78%)

5 Years

rr_AverageAnnualReturnYear05

4.65%

10 Years

rr_AverageAnnualReturnYear10

10.21%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2045 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.81%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

226

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

418

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 971

Annual Return 2009

rr_AnnualReturn2009

28.28%

Annual Return 2010

rr_AnnualReturn2010

15.10%

Annual Return 2011

rr_AnnualReturn2011

(3.88%)

Annual Return 2012

rr_AnnualReturn2012

17.26%

Annual Return 2013

rr_AnnualReturn2013

25.98%

Annual Return 2014

rr_AnnualReturn2014

4.28%

Annual Return 2015

rr_AnnualReturn2015

(0.12%)

Annual Return 2016

rr_AnnualReturn2016

7.77%

Annual Return 2017

rr_AnnualReturn2017

23.41%

Annual Return 2018

rr_AnnualReturn2018

(9.90%)

1 Year

rr_AverageAnnualReturnYear01

(9.90%)

5 Years

rr_AverageAnnualReturnYear05

4.53%

10 Years

rr_AverageAnnualReturnYear10

10.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2007

TIAA-CREF Lifecycle 2045 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(11.05%)

5 Years

rr_AverageAnnualReturnYear05

3.29%

10 Years

rr_AverageAnnualReturnYear10

9.12%

TIAA-CREF Lifecycle 2045 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.20%)

5 Years

rr_AverageAnnualReturnYear05

3.30%

10 Years

rr_AverageAnnualReturnYear10

8.11%

[1] As of the close of business on December 31, 2018, the Lifecycle 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI All Country World Index ex USA Investable Market Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

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TIAA-CREF Lifecycle Index 2055 Fund

TIAA-CREF Lifecycle Index 2055 Fund

Investment objective

The Lifecycle Index 2055 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2055 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2055 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.15%	0.15%	0.15%	0.15%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.07%	0.15%	0.06%	0.31%
Total annual Fund operating expenses		0.22%	0.30%	0.36%	0.46%
Waivers and expense reimbursements	[3],[4]	(0.12%)	(0.12%)	(0.11%)	(0.11%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2055 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	59	84	105	137
5 years	112	157	191	247
10 years	$ 268	$ 369	$ 445	$ 569

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2055 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 92.50% of the Fund’s assets to equity Underlying Funds and 7.50% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2055 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2085. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 64.75%; International Equity: 27.75%; Fixed-Income: 7.50%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Market Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	92.91%	U.S. Equity	65.16%	ŸEquity Index Fund	65.16%
		International Equity	27.75%	ŸInternational Equity Index Fund	19.90%
				ŸEmerging Markets Equity Index Fund	7.85%
Fixed-Income	7.09%	Fixed-Income	7.09%	ŸBond Index Fund	7.09%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2055 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.96%.

Best quarter: 11.36%, for the quarter ended March 31, 2012. Worst quarter: -12.23%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2055 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(7.32%)	5.39%		7.10%		Apr. 29, 2011
Institutional Class		(7.14%)	5.64%		7.36%		Apr. 29, 2011
Advisor Class		(7.11%)	5.53%	[1]	7.19%	[1]	Dec. 04, 2015
Premier Class		(7.21%)	5.50%		7.21%		Apr. 29, 2011
After Taxes on Distributions | Retirement Class		(7.86%)	4.81%		6.55%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(4.00%)	4.12%		5.58%
S&P Target Date 2055 Index		(7.97%)	5.07%		6.82%	[2]
Lifecycle Index 2055 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.24%)	5.71%		7.45%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.06% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.04% of average daily net assets for Institutional Class shares; (ii) 0.19% of average daily net assets for Advisor Class shares; (iii) 0.19% of average daily net assets for Premier Class shares; and (iv) 0.29% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI EAFE + Emerging Markets Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2015 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2015 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

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The Lifecycle 2015 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 21% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

21.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2015 and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 40.00% of the Fund’s assets to equity Underlying Funds, 55.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2015 (the direct real estate asset class was added in 2017) and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2045. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 39.00%; Short-Term Fixed-Income: 8.00%; Inflation-Protected Assets: 8.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	42.07%	U.S. Equity	29.51%	ŸGrowth & Income Fund	6.18%
				ŸLarge-Cap Growth Fund	5.59%
				ŸLarge-Cap Value Fund	5.42%
				ŸQuant Large-Cap Growth Fund	4.88%
				ŸQuant Large-Cap Value Fund	4.74%
				ŸQuant Small-Cap Equity Fund	1.51%
				ŸQuant Small/Mid-Cap Equity Fund	1.19%
		International Equity	12.56%	ŸQuant International Equity Fund	3.28%
				ŸInternational Equity Fund	2.73%
				ŸInternational Opportunities Fund	2.72%
				ŸEmerging Markets Equity Fund	2.15%
				ŸQuant International Small-Cap Equity Fund	1.68%
Fixed-Income	53.25%	Fixed-Income	37.34%	ŸBond Fund	19.13%
				ŸBond Plus Fund	12.48%
				ŸEmerging Markets Debt Fund	2.07%
				ŸInternational Bond Fund	2.00%
				ŸHigh-Yield Fund	1.66%
		Short-Term Fixed-Income	8.45%	ŸShort-Term Bond Fund	8.45%
		Inflation- Protected Assets	7.46%	ŸInflation-Linked Bond Fund	7.46%
Real Estate	4.68%	Direct Real Estate	4.68%	ŸTIAA-CREF Real Property Fund LP	4.68%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI All Country World Index ex USA Investable Market Index; 7.4% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2015 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.78%.

Bar Chart Closing [Text Block]

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Best quarter: 12.39%, for the quarter ended June 30, 2009. Worst quarter: -9.52%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.78%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

12.39%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.52%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2015 Fund | S&P Target Date 2015 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.67%)

5 Years

rr_AverageAnnualReturnYear05

3.79%

10 Years

rr_AverageAnnualReturnYear10

7.11%

TIAA-CREF Lifecycle 2015 Fund | Lifecycle 2015 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.48%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

4.12%

^[1]

10 Years

rr_AverageAnnualReturnYear10

7.74%

^[1]

TIAA-CREF Lifecycle 2015 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.43%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.50%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.38%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 39

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

126

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

246

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 596

1 Year

rr_AverageAnnualReturnYear01

(4.41%)

5 Years

rr_AverageAnnualReturnYear05

4.03%

10 Years

rr_AverageAnnualReturnYear10

8.08%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2015 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.43%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.58%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.46%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 47

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

152

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

290

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 694

1 Year

rr_AverageAnnualReturnYear01

(4.42%)

5 Years

rr_AverageAnnualReturnYear05

3.91%

^[7]

10 Years

rr_AverageAnnualReturnYear10

7.88%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2015 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.43%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.65%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

174

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

329

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 779

1 Year

rr_AverageAnnualReturnYear01

(4.60%)

5 Years

rr_AverageAnnualReturnYear05

3.87%

10 Years

rr_AverageAnnualReturnYear10

7.90%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2015 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.43%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.75%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.12%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.63%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 64

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

206

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

384

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 899

Annual Return 2009

rr_AnnualReturn2009

21.32%

Annual Return 2010

rr_AnnualReturn2010

12.36%

Annual Return 2011

rr_AnnualReturn2011

0.46%

Annual Return 2012

rr_AnnualReturn2012

13.31%

Annual Return 2013

rr_AnnualReturn2013

13.66%

Annual Return 2014

rr_AnnualReturn2014

4.45%

Annual Return 2015

rr_AnnualReturn2015

0.18%

Annual Return 2016

rr_AnnualReturn2016

6.11%

Annual Return 2017

rr_AnnualReturn2017

13.65%

Annual Return 2018

rr_AnnualReturn2018

(4.74%)

1 Year

rr_AverageAnnualReturnYear01

(4.74%)

5 Years

rr_AverageAnnualReturnYear05

3.75%

10 Years

rr_AverageAnnualReturnYear10

7.80%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2015 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.36%)

5 Years

rr_AverageAnnualReturnYear05

2.05%

10 Years

rr_AverageAnnualReturnYear10

6.39%

TIAA-CREF Lifecycle 2015 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.07%)

5 Years

rr_AverageAnnualReturnYear05

2.54%

10 Years

rr_AverageAnnualReturnYear10

5.99%

[1] As of the close of business on December 31, 2018, the Lifecycle 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI All Country World Index ex USA Investable Market Index; 7.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

TIAA-CREF Lifecycle 2050 Fund

TIAA-CREF Lifecycle 2050 Fund

Investment objective

The Lifecycle 2050 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2050 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2050 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.50%	0.50%	0.50%	0.50%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.12%	0.04%	0.29%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.57%	0.65%	0.72%	0.82%
Waivers and expense reimbursements	[4],[5]	(0.12%)	(0.12%)	(0.12%)	(0.12%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.45%	0.53%	0.60%	0.70%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2050 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 46	$ 54	$ 61	$ 72
3 years	149	174	197	228
5 years	285	329	367	422
10 years	$ 681	$ 779	$ 863	$ 982

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2050 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 91.25% of the Fund’s assets to equity Underlying Funds, 3.75% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2050 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2080. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.87%; International Equity: 27.38%; Fixed-Income: 3.75%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	91.63%	U.S. Equity	64.24%	ŸGrowth & Income Fund	13.47%
				ŸLarge-Cap Growth Fund	12.15%
				ŸLarge-Cap Value Fund	11.78%
				ŸQuant Large-Cap Growth Fund	10.63%
				ŸQuant Large-Cap Value Fund	10.32%
				ŸQuant Small-Cap Equity Fund	3.30%
				ŸQuant Small/Mid-Cap Equity Fund	2.59%
		International Equity	27.39%	ŸQuant International Equity Fund	7.15%
				ŸInternational Equity Fund	5.96%
				ŸInternational Opportunities Fund	5.94%
				ŸEmerging Markets Equity Fund	4.69%
				ŸQuant International Small-Cap Equity Fund	3.65%
Fixed-Income	3.76%	Fixed-Income	3.76%	ŸBond Fund	1.97%
				ŸBond Plus Fund	1.22%
				ŸEmerging Markets Debt Fund	0.31%
				ŸInternational Bond Fund	0.20%
				ŸHigh-Yield Fund	0.06%
Real Estate	4.61%	Direct Real Estate	4.61%	ŸTIAA-CREF Real Property Fund LP	4.61%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2050 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.25%.

Best quarter: 17.30%, for the quarter ended June 30, 2009. Worst quarter: -16.40%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2050 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(9.98%)	4.59%		10.11%		Nov. 30, 2007
Institutional Class		(9.82%)	4.85%		10.37%		Nov. 30, 2007
Advisor Class		(9.83%)	4.72%	[1]	10.17%	[1]	Dec. 04, 2015
Premier Class		(9.93%)	4.70%		10.20%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(11.10%)	3.37%		9.13%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(5.25%)	3.35%		8.13%
S&P Target Date 2050 Index		(7.94%)	5.01%		10.02%
Lifecycle 2050 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(7.38%)	5.59%		10.52%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2050 Fund Composite Index consisted of: 64.1% Russell 3000® Index; 27.5% MSCI All Country World Index ex USA Investable Market Index; and 8.4% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2010 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2010 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2010 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 19% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

19.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2010 and who may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 40.00% of the Fund’s assets to equity Underlying Funds and 60.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2010 and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2040. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 28.00%; International Equity: 12.00%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; and Inflation-Protected Assets: 10.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	41.75%	U.S. Equity	29.28%	ŸEquity Index Fund	29.28%
		International Equity	12.47%	ŸInternational Equity Index Fund	8.94%
				ŸEmerging Markets Equity Index Fund	3.53%
Fixed-Income	58.25%	Fixed-Income	39.34%	ŸBond Index Fund	39.34%
		Short-Term Fixed-Income	9.44%	ŸShort-Term Bond Index Fund	9.44%
		Inflation- Protected Assets	9.47%	ŸInflation-Linked Bond Fund	9.47%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifecycle Index 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI EAFE + Emerging Markets Index; 9.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2010 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.02%.

Bar Chart Closing [Text Block]

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Best quarter: 7.77%, for the quarter ended September 30, 2010. Worst quarter: -6.63%, for the quarter ended September 30, 2011.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.02%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.77%

Lowest Quarterly Return, Label

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Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(6.63%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2010 Fund | S&P Target Date 2010 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.10%)

5 Years

rr_AverageAnnualReturnYear05

3.40%

Since Inception

rr_AverageAnnualReturnSinceInception

5.50%

^[1]

TIAA-CREF Lifecycle Index 2010 Fund | Lifecycle Index 2010 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.94%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.01%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

6.33%

^[1],[2]

TIAA-CREF Lifecycle Index 2010 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.06%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.25%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.15%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

65

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

126

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 303

1 Year

rr_AverageAnnualReturnYear01

(2.87%)

5 Years

rr_AverageAnnualReturnYear05

3.94%

Since Inception

rr_AverageAnnualReturnSinceInception

6.20%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2010 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.33%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.15%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

91

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

170

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 403

1 Year

rr_AverageAnnualReturnYear01

(2.98%)

5 Years

rr_AverageAnnualReturnYear05

3.81%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

6.00%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2010 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.06%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.40%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.15%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

113

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

209

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 491

1 Year

rr_AverageAnnualReturnYear01

(3.10%)

5 Years

rr_AverageAnnualReturnYear05

3.77%

Since Inception

rr_AverageAnnualReturnSinceInception

6.04%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2010 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.19%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.31%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.50%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.15%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

145

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

265

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 614

Annual Return 2010

rr_AnnualReturn2010

10.48%

Annual Return 2011

rr_AnnualReturn2011

3.07%

Annual Return 2012

rr_AnnualReturn2012

10.21%

Annual Return 2013

rr_AnnualReturn2013

10.55%

Annual Return 2014

rr_AnnualReturn2014

5.98%

Annual Return 2015

rr_AnnualReturn2015

(0.29%)

Annual Return 2016

rr_AnnualReturn2016

5.56%

Annual Return 2017

rr_AnnualReturn2017

10.82%

Annual Return 2018

rr_AnnualReturn2018

(3.15%)

1 Year

rr_AverageAnnualReturnYear01

(3.15%)

5 Years

rr_AverageAnnualReturnYear05

3.67%

Since Inception

rr_AverageAnnualReturnSinceInception

5.92%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2010 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.03%)

5 Years

rr_AverageAnnualReturnYear05

2.92%

Since Inception

rr_AverageAnnualReturnSinceInception

5.24%

TIAA-CREF Lifecycle Index 2010 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.65%)

5 Years

rr_AverageAnnualReturnYear05

2.60%

Since Inception

rr_AverageAnnualReturnSinceInception

4.51%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI EAFE + Emerging Markets Index; 9.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.102% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

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TIAA-CREF Lifestyle Moderate Fund

TIAA-CREF Lifestyle Moderate Fund

Investment objective

The Fund seeks long-term total return, consisting of capital appreciation and current income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifestyle Moderate Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifestyle Moderate Fund		Institutional Class	Advisor Class		Premier Class	Retirement Class	Retail Class
Management fees		0.10%	0.10%		0.10%	0.10%	0.10%
Distribution (Rule 12b-1) fees					0.15%		0.25%
Other expenses		0.07%	0.15%	[1]	0.07%	0.32%	0.08%
Acquired Fund fees and expenses	[2]	0.40%	0.40%		0.40%	0.40%	0.40%
Total annual Fund operating expenses		0.57%	0.65%		0.72%	0.82%	0.83%
Waivers and expense reimbursements	[3]	(0.07%)	(0.07%)		(0.07%)	(0.07%)	(0.06%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.50%	0.58%		0.65%	0.75%	0.77%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifestyle Moderate Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 51	$ 59	$ 66	$ 77	$ 79
3 years	176	201	223	255	259
5 years	311	355	394	448	455
10 years	$ 707	$ 804	$ 888	$ 1,007	$ 1,020

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term total return, consisting of capital appreciation and current income, through a relatively stable asset allocation strategy targeting a moderate risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 60% of the Fund’s assets in equity Underlying Funds and (2) approximately 40% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.66%	U.S. Equity	43.54%	ŸLarge-Cap Growth Fund	10.74%
				ŸLarge-Cap Value Fund	10.40%
				ŸGrowth & Income Fund	9.52%
				ŸQuant Large-Cap Growth Fund	6.02%
				ŸQuant Large-Cap Value Fund	2.90%
				ŸQuant Small-Cap Equity Fund	2.13%
				ŸQuant Small/Mid-Cap Equity Fund	1.83%
		International Equity	17.12%	ŸInternational Equity Fund	4.72%
				ŸInternational Opportunities Fund	3.92%
				ŸEmerging Markets Equity Fund	3.10%
				ŸQuant International Equity Fund	2.97%
				ŸQuant International Small-Cap Equity Fund	2.41%
Fixed-Income	39.34%	Fixed-Income	39.34%	ŸBond Plus Fund	39.34%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Moderate Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.34%.

Best quarter: 9.36%, for the quarter ended March 31, 2012. Worst quarter: -9.55%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifestyle Moderate Fund		1 Year	5 Years		Since Inception		Inception Date
Institutional Class		(6.95%)	4.12%		7.28%		Dec. 09, 2011
Advisor Class		(7.00%)	4.08%	[1]	7.25%	[1]	Dec. 04, 2015
Premier Class		(7.12%)	3.99%		7.13%		Dec. 09, 2011
Retirement Class		(7.19%)	3.87%		7.02%		Dec. 09, 2011
Retail Class		(7.28%)	3.83%		6.97%		Dec. 09, 2011
After Taxes on Distributions | Institutional Class		(8.19%)	2.79%		6.01%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(3.58%)	2.83%		5.40%
Morningstar Moderate Target Risk Index (reflects no deductions for fees, expenses or taxes)		(4.76%)	4.08%		6.57%	[2]
Lifestyle Moderate Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(4.69%)	4.61%		7.01%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Restated to reflect estimate for the current fiscal year.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

[2] Performance is calculated from the inception date of the Institutional Class.

[3] As of the close of business on December 31, 2018, the Lifestyle Moderate Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifestyle Income Fund

TIAA-CREF Lifestyle Income Fund

Investment objective

The Fund seeks current income with some capital appreciation.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifestyle Income Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifestyle Income Fund		Institutional Class	Advisor Class		Premier Class	Retirement Class	Retail Class
Management fees		0.10%	0.10%		0.10%	0.10%	0.10%
Distribution (Rule 12b-1) fees					0.15%		0.25%
Other expenses		0.26%	0.33%	[1]	0.26%	0.50%	0.28%
Acquired Fund fees and expenses	[2]	0.32%	0.32%		0.32%	0.32%	0.32%
Total annual Fund operating expenses		0.68%	0.75%		0.83%	0.92%	0.95%
Waivers and expense reimbursements	[3]	(0.26%)	(0.25%)		(0.26%)	(0.25%)	(0.25%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.42%	0.50%		0.57%	0.67%	0.70%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifestyle Income Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 43	$ 51	$ 58	$ 68	$ 72
3 years	191	215	239	268	278
5 years	353	392	435	485	501
10 years	$ 822	$ 907	$ 1,001	$ 1,108	$ 1,144

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking current income with some capital appreciation through a relatively stable asset allocation strategy targeting an income-oriented and conservative risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 20% of the Fund’s assets in equity Underlying Funds and (2) approximately 80% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	20.46%	U.S. Equity	15.33%	ŸLarge-Cap Growth Fund	3.63%
				ŸLarge-Cap Value Fund	3.52%
				ŸQuant Large-Cap Growth Fund	3.32%
				ŸGrowth & Income Fund	3.21%
				ŸQuant Small-Cap Equity Fund	0.72%
				ŸQuant Small/Mid-Cap Equity Fund	0.62%
				ŸQuant Large-Cap Value Fund	0.31%
		International Equity	5.13%	ŸInternational Equity Fund	1.59%
				ŸInternational Opportunities Fund	1.32%
				ŸEmerging Markets Equity Fund	1.05%
				ŸQuant International Small-Cap Equity Fund	0.82%
				ŸQuant International Equity Fund	0.35%
Fixed-Income	79.54%	Fixed-Income	38.85%	ŸBond Plus Fund	19.93%
				ŸBond Fund	18.92%
		Short-Term Fixed-Income	40.69%	ŸShort-Term Bond Fund	40.69%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a higher percentage of fixed-income Underlying Funds, Fixed-Income Underlying Funds Risks are expected to predominate.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Income Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 7.44%.

Best quarter: 3.94%, for the quarter ended March 31, 2012. Worst quarter: -2.77%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifestyle Income Fund		1 Year	5 Years		Since Inception		Inception Date
Institutional Class		(2.04%)	2.74%		3.87%		Dec. 09, 2011
Advisor Class		(2.04%)	2.72%	[1]	3.86%	[1]	Dec. 04, 2015
Premier Class		(2.26%)	2.57%		3.71%		Dec. 09, 2011
Retirement Class		(2.27%)	2.48%		3.61%		Dec. 09, 2011
Retail Class		(2.30%)	2.44%		3.58%		Dec. 09, 2011
After Taxes on Distributions | Institutional Class		(3.22%)	1.58%		2.74%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(0.97%)	1.69%		2.60%
Morningstar Conservative Target Risk Index (reflects no deductions for fees, expenses or taxes)		(1.20%)	2.54%		3.31%	[2]
Lifestyle Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(0.87%)	2.66%		3.38%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Restated to reflect estimate for the current fiscal year.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

[2] Performance is calculated from the inception date of the Institutional Class.

[3] As of the close of business on December 31, 2018, the Lifestyle Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 40.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; 14.0% Russell 3000® Index; and 6.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Retirement Income Fund

TIAA-CREF Lifecycle Retirement Income Fund

Investment objective

The Lifecycle Retirement Income Fund seeks high total return over time primarily through income,

with a secondary emphasis on capital appreciation.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Retirement Income Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Retirement Income Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Management fees	[1],[2]	0.42%	0.42%	0.42%	0.42%	0.42%
Distribution (Rule 12b-1) fees				0.15%		0.25%
Other expenses	[1],[2]	0.08%	0.16%	0.08%	0.33%	0.11%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.53%	0.61%	0.68%	0.78%	0.81%
Waivers and expense reimbursements	[4],[5]	(0.16%)	(0.16%)	(0.16%)	(0.16%)	(0.19%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.37%	0.45%	0.52%	0.62%	0.62%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Retirement Income Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 38	$ 46	$ 53	$ 63	$ 63
3 years	132	158	180	212	218
5 years	259	303	341	396	410
10 years	$ 629	$ 726	$ 811	$ 931	$ 964

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 25% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy that will not gradually adjust over time and is designed for investors who are already in retirement (i.e., have already passed their retirement year) and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 35.00% of the Fund’s assets to equity Underlying Funds, 60.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations may be changed and actual allocations may vary up to ten percentage points from the targets. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020 which may change, are approximately as follows: U.S. Equity: 24.50%; International Equity: 10.50%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; Inflation-Protected Assets: 10.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change. Investors should note that the Fund has a significant level of equity exposure and this exposure could cause fluctuation in the value of the Fund depending on the performance of the equity markets generally.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. The Fund has relatively fixed asset allocations that will not gradually adjust over time. Underlying Fund allocations may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	36.02%	U.S. Equity	25.26%	ŸGrowth & Income Fund	5.30%
				ŸLarge-Cap Growth Fund	4.78%
				ŸLarge-Cap Value Fund	4.63%
				ŸQuant Large-Cap Growth Fund	4.18%
				ŸQuant Large-Cap Value Fund	4.06%
				ŸQuant Small-Cap Equity Fund	1.29%
				ŸQuant Small/Mid-Cap Equity Fund	1.02%
		International Equity	10.76%	ŸQuant International Equity Fund	2.81%
				ŸInternational Equity Fund	2.34%
				ŸInternational Opportunities Fund	2.34%
				ŸEmerging Markets Equity Fund	1.84%
				ŸQuant International Small-Cap Equity Fund	1.43%
Fixed-Income	59.35%	Fixed-Income	38.61%	ŸBond Fund	19.80%
				ŸBond Plus Fund	12.88%
				ŸEmerging Markets Debt Fund	2.13%
				ŸInternational Bond Fund	2.07%
				ŸHigh-Yield Fund	1.73%
		Short-Term Fixed-Income	10.85%	ŸShort-Term Bond Fund	10.85%
		Inflation- Protected Assets	9.89%	ŸInflation-Linked Bond Fund	9.89%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor, Premier and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Retirement Income Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 9.91%.

Best quarter: 8.88%, for the quarter ended September 30, 2009. Worst quarter: -6.10%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Retirement Income Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(4.01%)	3.41%		6.60%		Nov. 30, 2007
Institutional Class		(3.84%)	3.67%		6.86%		Nov. 30, 2007
Advisor Class		(3.80%)	3.56%	[1]	6.68%	[1]	Dec. 04, 2015
Premier Class		(3.90%)	3.52%		6.70%	[1]	Sep. 30, 2009
Retail Class		(4.00%)	3.40%		6.63%		Nov. 30, 2007
After Taxes on Distributions | Retirement Class		(5.55%)	2.07%		5.45%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(1.77%)	2.25%		4.93%
S&P Target Date Retirement Income Index		(2.54%)	3.06%		5.31%
Lifecycle Retirement Income Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(2.94%)	3.71%		6.55%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; (iv) 0.25% of average daily net assets for Retirement Class shares; and (v) 0.25% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle Retirement Income Fund Composite Index consisted of: 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; 28.0% Russell 3000® Index; 12.0% MSCI All Country World Index ex USA Investable Market Index; 10.0% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 10.0% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2020 Fund

TIAA-CREF Lifecycle 2020 Fund

Investment objective

The Lifecycle 2020 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle 2020 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle 2020 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.44%	0.44%	0.44%	0.44%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.12%	0.04%	0.29%
Acquired Fund fees and expenses	[3]	0.03%	0.03%	0.03%	0.03%
Total annual Fund operating expenses		0.51%	0.59%	0.66%	0.76%
Waivers and expense reimbursements	[4],[5]	(0.12%)	(0.12%)	(0.12%)	(0.12%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.39%	0.47%	0.54%	0.64%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle 2020 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 40	$ 48	$ 55	$ 65
3 years	130	155	177	209
5 years	252	296	334	389
10 years	$ 608	$ 706	$ 791	$ 911

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2020 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 45.00% of the Fund’s assets to equity Underlying Funds, 50.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2020 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2050. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 31.50%; International Equity: 13.50%; Fixed-Income: 38.00%; Short-Term Fixed-Income: 6.00%; Inflation-Protected Assets: 6.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	47.90%	U.S. Equity	33.60%	ŸGrowth & Income Fund	7.03%
				ŸLarge-Cap Growth Fund	6.38%
				ŸLarge-Cap Value Fund	6.17%
				ŸQuant Large-Cap Growth Fund	5.55%
				ŸQuant Large-Cap Value Fund	5.40%
				ŸQuant Small-Cap Equity Fund	1.72%
				ŸQuant Small/Mid-Cap Equity Fund	1.35%
		International Equity	14.30%	ŸQuant International Equity Fund	3.73%
				ŸInternational Equity Fund	3.11%
				ŸInternational Opportunities Fund	3.10%
				ŸEmerging Markets Equity Fund	2.45%
				ŸQuant International Small-Cap Equity Fund	1.91%
Fixed-Income	47.43%	Fixed-Income	35.46%	ŸBond Fund	18.15%
				ŸBond Plus Fund	11.86%
				ŸEmerging Markets Debt Fund	1.98%
				ŸInternational Bond Fund	1.90%
				ŸHigh-Yield Fund	1.57%
		Short-Term Fixed-Income	6.47%	ŸShort-Term Bond Fund	6.47%
		Inflation- Protected Assets	5.50%	ŸInflation-Linked Bond Fund	5.50%
Real Estate	4.67%	Direct Real Estate	4.67%	ŸTIAA-CREF Real Property Fund LP	4.67%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2020 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 11.48%.

Best quarter: 13.85%, for the quarter ended June 30, 2009. Worst quarter: -11.24%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle 2020 Fund		1 Year	5 Years		10 Years		Inception Date
Retirement Class		(5.38%)	3.97%		8.39%		Oct. 15, 2004
Institutional Class		(5.18%)	4.24%		8.66%		Jan. 17, 2007
Advisor Class		(5.15%)	4.11%	[1]	8.46%	[1]	Dec. 04, 2015
Premier Class		(5.26%)	4.08%		8.50%	[1]	Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(6.97%)	2.35%		7.07%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(2.42%)	2.74%		6.53%
S&P Target Date 2020 Index		(4.16%)	4.10%		7.86%
Lifecycle 2020 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[2]	(3.97%)	4.41%		8.37%

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[5] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

[2] As of the close of business on December 31, 2018, the Lifecycle 2020 Fund Composite Index consisted of: 36.8% Bloomberg Barclays U.S. Aggregate Bond Index; 36.7% Russell 3000® Index; 15.7% MSCI All Country World Index ex USA Investable Market Index; 5.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 5.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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Label

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TIAA-CREF Managed Allocation Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Managed Allocation Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Fund seeks favorable returns that reflect the broad investment performance of the financial markets through capital appreciation and investment income. The Fund will pursue this goal through a “fund of funds” approach, whereby the Fund will make investments primarily in other mutual funds.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Portfolio Turnover, Rate

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20.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund invests in Underlying Funds according to a relatively stable asset allocation strategy and will generally seek to meet its investment objective by investing: (1) approximately 60.00% of its assets in equity Underlying Funds, including up to 5.00% of its assets in real estate Underlying Funds; and (2) approximately 40.00% of its assets in fixed-income Underlying Funds (“target allocations”).

The Fund may invest in the following equity Underlying Funds: TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant International Equity Fund, Quant International Small-Cap Equity Fund, Quant Small-Cap Equity Fund, Quant Small/Mid-Cap Equity Fund, Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund and Real Estate Securities Fund.

The Fund may invest in the following fixed-income Underlying Funds: TIAA-CREF Bond Plus Fund, High-Yield Fund, Inflation-Linked Bond Fund, International Bond Fund, Money Market Fund and Short-Term Bond Fund.

As a result of its investments in the Underlying Funds, the Managed Allocation Fund’s returns will reflect investments in a mix of domestic stocks of companies of all sizes, foreign equities, real estate securities and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the foreign and domestic equity markets, as well as overall financial and economic conditions. If the portfolio managers believe that the relative attractiveness of the markets in which the equity and fixed-income funds are invested changes, they can adjust the percentage of investments in the Fund’s market sectors or Underlying Funds up or down by up to 10%; they may also invest in new market sectors or Underlying Funds without prior notice. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above or in the chart below, shareholders will receive prior notice of such change. At any given time the Fund may hold between 0% to 5% of its assets in real estate funds. The

Fund’s composite benchmark is a composite of three benchmark indices representing three types of market sectors within the equity and fixed-income Underlying Fund asset classes, i.e., domestic equity, international equity and fixed-income. The composite index is created by applying the results of the benchmark for each of these three market sectors in proportion to the Fund’s target allocations among the three market sectors. For more information about the different indices that comprise the Fund’s composite benchmark index, please see “Additional information about the Fund’s composite index” below.

The composition of the Fund’s fixed-income portion will vary depending on the shape of the yield curve. This means that when there is not much difference between the yield on short-term and long-term bonds, the Fund would normally increase its investments in the Short-Term Bond Fund. The Fund will have less than 5% of its assets in the High-Yield Fund.

The Fund might sometimes be even more heavily weighted toward equities or fixed-income, if Advisors believes market conditions warrant. For example, the Fund might increase its holdings in fixed-income funds in periods when Advisors believes equity markets will decline.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Board has authorized the Fund to invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”). The Fund may use investments in ETFs and ETNs to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

For flexibility in meeting redemptions, expenses and the timing of new investments, and as a short-term defense during periods of unusual volatility, the Fund may invest in government securities (as defined in the Investment Company Act of 1940, as amended (the “1940 Act”)), short-term paper or shares of the Money Market Fund. For temporary defensive purposes, the Managed Allocation Fund may invest without limitation in such securities. The Fund cannot guarantee that this strategy will be successful.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	60.65%	U.S. Equity	43.54%	ŸQuant Large-Cap Growth Fund	8.99%
				ŸGrowth & Income Fund	8.93%
				ŸLarge-Cap Growth Fund	8.07%
				ŸLarge-Cap Value Fund	7.81%
				ŸQuant Large-Cap Value Fund	5.84%
				ŸQuant Small-Cap Equity Fund	2.19%
				ŸQuant Small/Mid-Cap Equity Fund	1.71%
		International Equity	17.11%	ŸInternational Equity Fund	3.93%
				ŸInternational Opportunities Fund	3.93%
				ŸQuant International Equity Fund	3.74%
				ŸEmerging Markets Equity Fund	3.10%
				ŸQuant International Small-Cap Equity Fund	2.41%
Fixed-Income	39.35%	Fixed-Income	39.35%	ŸBond Plus Fund	39.35%

Total 100.00% 100.00% 100.00%

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. Accordingly, an investment in the Fund or the Underlying Funds typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Managed Allocation Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)†

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.22%.

Bar Chart Closing [Text Block]

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Best quarter: 12.65%, for the quarter ended June 30, 2009. Worst quarter: -10.49%, for the quarter ended September 30, 2011.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

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Jun. 30, 2019

Bar Chart, Year to Date Return

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13.22%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

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Jun. 30, 2009

Highest Quarterly Return

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12.65%

Lowest Quarterly Return, Label

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Worst quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(10.49%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Managed Allocation Fund | Morningstar Moderate Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.76%)

5 Years

rr_AverageAnnualReturnYear05

4.08%

10 Years

rr_AverageAnnualReturnYear10

7.97%

TIAA-CREF Managed Allocation Fund | Managed Allocation Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.69%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

4.61%

^[1]

10 Years

rr_AverageAnnualReturnYear10

8.29%

^[1]

TIAA-CREF Managed Allocation Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Other expenses

rr_OtherExpensesOverAssets

0.03%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.39%

^[2]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.42%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.03%)

^[3]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.39%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 40

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

132

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

232

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 527

Annual Return 2009

rr_AnnualReturn2009

22.46%

Annual Return 2010

rr_AnnualReturn2010

13.44%

Annual Return 2011

rr_AnnualReturn2011

0.31%

Annual Return 2012

rr_AnnualReturn2012

14.65%

Annual Return 2013

rr_AnnualReturn2013

16.96%

Annual Return 2014

rr_AnnualReturn2014

5.16%

Annual Return 2015

rr_AnnualReturn2015

0.56%

Annual Return 2016

rr_AnnualReturn2016

6.93%

Annual Return 2017

rr_AnnualReturn2017

17.07%

Annual Return 2018

rr_AnnualReturn2018

(6.82%)

1 Year

rr_AverageAnnualReturnYear01

(6.82%)

5 Years

rr_AverageAnnualReturnYear05

4.29%

10 Years

rr_AverageAnnualReturnYear10

8.71%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2006

TIAA-CREF Managed Allocation Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(8.36%)

5 Years

rr_AverageAnnualReturnYear05

2.62%

10 Years

rr_AverageAnnualReturnYear10

7.34%

TIAA-CREF Managed Allocation Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.32%)

5 Years

rr_AverageAnnualReturnYear05

2.92%

10 Years

rr_AverageAnnualReturnYear10

6.68%

TIAA-CREF Managed Allocation Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Other expenses

rr_OtherExpensesOverAssets

0.28%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.39%

^[2]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.67%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.03%)

^[3]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.64%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 65

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

211

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

370

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 832

1 Year

rr_AverageAnnualReturnYear01

(6.99%)

5 Years

rr_AverageAnnualReturnYear05

4.03%

10 Years

rr_AverageAnnualReturnYear10

8.43%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2006

TIAA-CREF Managed Allocation Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.07%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.39%

^[2]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.71%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[3]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.64%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 65

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

220

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

388

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 876

1 Year

rr_AverageAnnualReturnYear01

(6.96%)

5 Years

rr_AverageAnnualReturnYear05

4.03%

10 Years

rr_AverageAnnualReturnYear10

8.47%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2006

[1] As of the close of business on December 31, 2018, the Managed Allocation Fund Composite Index consisted of: 42.0% Russell 3000® Index; 40.0% Bloomberg Barclays U.S. Aggregate Bond Index; and 18.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Retirement Class shares; and (iii) 0.25% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2010 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2010 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2010 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 22% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

22.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2010 and may have begun taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 35.00% of the Fund’s assets to equity Underlying Funds, 60.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2010 (the direct real estate asset class was added in 2017) and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2040. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 24.50%; International Equity: 10.50%; Fixed-Income: 40.00%; Short-Term Fixed-Income: 10.00%; Inflation-Protected Assets: 10.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	37.05%	U.S. Equity	25.99%	ŸGrowth & Income Fund	5.44%
				ŸLarge-Cap Growth Fund	4.93%
				ŸLarge-Cap Value Fund	4.77%
				ŸQuant Large-Cap Growth Fund	4.29%
				ŸQuant Large-Cap Value Fund	4.18%
				ŸQuant Small-Cap Equity Fund	1.33%
				ŸQuant Small/Mid-Cap Equity Fund	1.05%
		International Equity	11.06%	ŸQuant International Equity Fund	2.89%
				ŸInternational Equity Fund	2.40%
				ŸInternational Opportunities Fund	2.40%
				ŸEmerging Markets Equity Fund	1.90%
				ŸQuant International Small-Cap Equity Fund	1.47%
Fixed-Income	58.27%	Fixed-Income	38.38%	ŸBond Fund	19.68%
				ŸBond Plus Fund	12.82%
				ŸEmerging Markets Debt Fund	2.12%
				ŸInternational Bond Fund	2.05%
				ŸHigh-Yield Fund	1.71%
		Short-Term Fixed-Income	10.43%	ŸShort-Term Bond Fund	10.43%
		Inflation- Protected Assets	9.46%	ŸInflation-Linked Bond Fund	9.46%
Real Estate	4.68%	Direct Real Estate	4.68%	ŸTIAA-CREF Real Property Fund LP	4.68%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI All Country World Index ex USA Investable Market Index; 9.4% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2010 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.08%.

Bar Chart Closing [Text Block]

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Best quarter: 10.87%, for the quarter ended June 30, 2009. Worst quarter: -7.99%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.08%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

10.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.99%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2010 Fund | S&P Target Date 2010 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.10%)

5 Years

rr_AverageAnnualReturnYear05

3.40%

10 Years

rr_AverageAnnualReturnYear10

6.24%

TIAA-CREF Lifecycle 2010 Fund | Lifecycle 2010 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.05%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

3.90%

^[1]

10 Years

rr_AverageAnnualReturnYear10

7.19%

^[1]

TIAA-CREF Lifecycle 2010 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.05%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.50%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.37%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 38

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

125

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

245

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 595

1 Year

rr_AverageAnnualReturnYear01

(3.92%)

5 Years

rr_AverageAnnualReturnYear05

3.85%

10 Years

rr_AverageAnnualReturnYear10

7.56%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2010 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.13%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.58%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

151

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

289

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 693

1 Year

rr_AverageAnnualReturnYear01

(3.94%)

5 Years

rr_AverageAnnualReturnYear05

3.73%

^[7]

10 Years

rr_AverageAnnualReturnYear10

7.37%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2010 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.05%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.65%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.52%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 53

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

173

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

328

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 778

1 Year

rr_AverageAnnualReturnYear01

(4.09%)

5 Years

rr_AverageAnnualReturnYear05

3.68%

10 Years

rr_AverageAnnualReturnYear10

7.39%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2010 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.42%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.30%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.75%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.62%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 63

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

205

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

383

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 898

Annual Return 2009

rr_AnnualReturn2009

19.36%

Annual Return 2010

rr_AnnualReturn2010

11.53%

Annual Return 2011

rr_AnnualReturn2011

1.48%

Annual Return 2012

rr_AnnualReturn2012

12.27%

Annual Return 2013

rr_AnnualReturn2013

11.78%

Annual Return 2014

rr_AnnualReturn2014

4.38%

Annual Return 2015

rr_AnnualReturn2015

0.07%

Annual Return 2016

rr_AnnualReturn2016

5.98%

Annual Return 2017

rr_AnnualReturn2017

12.39%

Annual Return 2018

rr_AnnualReturn2018

(4.11%)

1 Year

rr_AverageAnnualReturnYear01

(4.11%)

5 Years

rr_AverageAnnualReturnYear05

3.59%

10 Years

rr_AverageAnnualReturnYear10

7.30%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2010 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.61%)

5 Years

rr_AverageAnnualReturnYear05

2.22%

10 Years

rr_AverageAnnualReturnYear10

6.16%

TIAA-CREF Lifecycle 2010 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(1.86%)

5 Years

rr_AverageAnnualReturnYear05

2.39%

10 Years

rr_AverageAnnualReturnYear10

5.53%

[1] As of the close of business on December 31, 2018, the Lifecycle 2010 Fund Composite Index consisted of: 39.7% Bloomberg Barclays U.S. Aggregate Bond Index; 29.0% Russell 3000® Index; 12.5% MSCI All Country World Index ex USA Investable Market Index; 9.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 9.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

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TIAA-CREF Lifecycle Index 2045 Fund

TIAA-CREF Lifecycle Index 2045 Fund

Investment objective

The Lifecycle Index 2045 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2045 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2045 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.15%	0.15%	0.15%	0.15%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.04%	0.14%	0.04%	0.29%
Total annual Fund operating expenses		0.19%	0.29%	0.34%	0.44%
Waivers and expense reimbursements	[3],[4]	(0.09%)	(0.10%)	(0.09%)	(0.09%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.19%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2045 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 19	$ 26	$ 36
3 years	52	83	100	132
5 years	98	153	182	237
10 years	$ 234	$ 358	$ 422	$ 546

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2045 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 90.00% of the Fund’s assets to equity Underlying Funds and 10.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2045 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2075. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 63.00%; International Equity: 27.00%; Fixed-Income: 10.00; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	90.44%	U.S. Equity	63.43%	ŸEquity Index Fund	63.43%
		International Equity	27.01%	ŸInternational Equity Index Fund	19.37%
				ŸEmerging Markets Equity Index Fund	7.64%
Fixed-Income	9.56%	Fixed-Income	9.56%	ŸBond Index Fund	9.56%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2045 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.76%.

Best quarter: 11.95%, for the quarter ended September 30, 2010. Worst quarter: -14.77%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2045 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(7.12%)	5.26%		8.72%		Sep. 30, 2009
Institutional Class		(6.92%)	5.52%		8.98%		Sep. 30, 2009
Advisor Class		(7.04%)	5.38%	[1]	8.78%	[1]	Dec. 04, 2015
Premier Class		(7.04%)	5.37%		8.83%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(7.67%)	4.66%		8.19%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(3.87%)	4.01%		7.02%
S&P Target Date 2045 Index		(7.74%)	4.91%		8.49%	[2]
Lifecycle Index 2045 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(7.03%)	5.59%		9.10%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.062% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.038% of average daily net assets for Institutional Class shares; (ii) 0.188% of average daily net assets for Advisor Class shares; (iii) 0.188% of average daily net assets for Premier Class shares; and (iv) 0.288% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2045 Fund Composite Index consisted of: 63.3% Russell 3000® Index; 27.1% MSCI EAFE + Emerging Markets Index; and 9.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2025 Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifecycle 2025 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle 2025 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

20.00%

Expenses Restated to Reflect Current [Text]

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Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2025 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 54.00% of the Fund’s assets to equity Underlying Funds, 41.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2025 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2055. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 37.80%; International Equity: 16.20%; Fixed-Income: 33.00%; Short-Term Fixed-Income: 4.00%; Inflation-Protected Assets: 4.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	56.78%	U.S. Equity	39.82%	ŸGrowth & Income Fund	8.34%
				ŸLarge-Cap Growth Fund	7.56%
				ŸLarge-Cap Value Fund	7.30%
				ŸQuant Large-Cap Growth Fund	6.57%
				ŸQuant Large-Cap Value Fund	6.40%
				ŸQuant Small-Cap Equity Fund	2.05%
				ŸQuant Small/Mid-Cap Equity Fund	1.60%
		International Equity	16.96%	ŸQuant International Equity Fund	4.42%
				ŸInternational Equity Fund	3.69%
				ŸInternational Opportunities Fund	3.68%
				ŸEmerging Markets Equity Fund	2.91%
				ŸQuant International Small-Cap Equity Fund	2.26%
Fixed-Income	38.57%	Fixed-Income	30.54%	ŸBond Fund	15.57%
				ŸBond Plus Fund	10.25%
				ŸEmerging Markets Debt Fund	1.75%
				ŸInternational Bond Fund	1.65%
				ŸHigh-Yield Fund	1.32%
		Short-Term Fixed-Income	4.51%	ŸShort-Term Bond Fund	4.51%
		Inflation- Protected Assets	3.52%	ŸInflation-Linked Bond Fund	3.52%
Real Estate	4.65%	Direct Real Estate	4.65%	ŸTIAA-CREF Real Property Fund LP	4.65%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifecycle 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI All Country World Index ex USA Investable Market Index; 3.4% Bloomberg Barclays U.S. 1–3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

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www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2025 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 12.56%.

Bar Chart Closing [Text Block]

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Best quarter: 15.33%, for the quarter ended June 30, 2009. Worst quarter: -12.93%, for the quarter ended September 30, 2011.

Year to Date Return, Label

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The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

12.56%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.33%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(12.93%)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.
 

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2025 Fund | S&P Target Date 2025 Index

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

(5.02%)

5 Years

rr_AverageAnnualReturnYear05

4.31%

10 Years

rr_AverageAnnualReturnYear10

8.46%

TIAA-CREF Lifecycle 2025 Fund | Lifecycle 2025 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

(4.66%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

4.71%

^[1]

10 Years

rr_AverageAnnualReturnYear10

9.00%

^[1]

TIAA-CREF Lifecycle 2025 Fund | Institutional Class

Risk/Return:

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Maximum sales charge imposed on purchases (percentage of offering price)

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none

Maximum deferred sales charge

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none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

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none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

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0.45%

^[2],[3]

Other expenses

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0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.52%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.41%

Expense Example, with Redemption, 1 Year

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$ 42

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

134

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

258

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 621

1 Year

rr_AverageAnnualReturnYear01

(6.05%)

5 Years

rr_AverageAnnualReturnYear05

4.43%

10 Years

rr_AverageAnnualReturnYear10

9.23%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2025 Fund | Advisor Class

Risk/Return:

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Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.45%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.60%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.49%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 50

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

159

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

302

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 719

1 Year

rr_AverageAnnualReturnYear01

(6.19%)

5 Years

rr_AverageAnnualReturnYear05

4.27%

^[7]

10 Years

rr_AverageAnnualReturnYear10

9.01%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2025 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.45%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.04%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.67%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.56%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 57

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

182

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

341

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 804

1 Year

rr_AverageAnnualReturnYear01

(6.23%)

5 Years

rr_AverageAnnualReturnYear05

4.27%

10 Years

rr_AverageAnnualReturnYear10

9.04%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2025 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.45%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.77%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.66%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 67

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

213

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

396

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 924

Annual Return 2009

rr_AnnualReturn2009

24.96%

Annual Return 2010

rr_AnnualReturn2010

13.88%

Annual Return 2011

rr_AnnualReturn2011

(1.56%)

Annual Return 2012

rr_AnnualReturn2012

15.24%

Annual Return 2013

rr_AnnualReturn2013

19.12%

Annual Return 2014

rr_AnnualReturn2014

4.56%

Annual Return 2015

rr_AnnualReturn2015

0.12%

Annual Return 2016

rr_AnnualReturn2016

6.74%

Annual Return 2017

rr_AnnualReturn2017

17.06%

Annual Return 2018

rr_AnnualReturn2018

(6.35%)

1 Year

rr_AverageAnnualReturnYear01

(6.35%)

5 Years

rr_AverageAnnualReturnYear05

4.14%

10 Years

rr_AverageAnnualReturnYear10

8.95%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2025 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.87%)

5 Years

rr_AverageAnnualReturnYear05

2.56%

10 Years

rr_AverageAnnualReturnYear10

7.66%

TIAA-CREF Lifecycle 2025 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.97%)

5 Years

rr_AverageAnnualReturnYear05

2.90%

10 Years

rr_AverageAnnualReturnYear10

7.03%

[1] As of the close of business on December 31, 2018, the Lifecycle 2025 Fund Composite Index consisted of: 42.3% Russell 3000® Index; 32.8% Bloomberg Barclays U.S. Aggregate Bond Index; 18.1% MSCI All Country World Index ex USA Investable Market Index; 3.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 3.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

Label

Element

Value

TIAA-CREF Lifestyle Aggressive Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifestyle Aggressive Growth Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 24% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

24.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term growth of capital through a relatively stable asset allocation strategy targeting an aggressive growth risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 100% of the Fund’s assets in equity Underlying Funds and (2) approximately 0% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	100.00%	U.S. Equity	71.06%	ŸLarge-Cap Growth Fund	17.67%
				ŸLarge-Cap Value Fund	17.18%
				ŸGrowth & Income Fund	15.68%
				ŸQuant Large-Cap Growth Fund	8.61%
				ŸQuant Large-Cap Value Fund	5.44%
				ŸQuant Small-Cap Equity Fund	3.47%
				ŸQuant Small/Mid-Cap Equity Fund	3.01%
		International Equity	28.94%	ŸInternational Equity Fund	7.80%
				ŸInternational Opportunities Fund	6.50%
				ŸQuant International Equity Fund	5.52%
				ŸEmerging Markets Equity Fund	5.13%
				ŸQuant International Small-Cap Equity Fund	3.99%

Total 100.00% 100.00% 100.00%

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a significantly higher percentage of equity Underlying Funds, Equity Underlying Funds Risks are expected to predominate.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifestyle Aggressive Growth Fund Composite Index consisted of: 70.0% Russell 3000® Index; and 30.0% MSCI All Country World Index ex USA Investable Market Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Aggressive Growth Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 17.61%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 14.33%, for the quarter ended March 31, 2012. Worst quarter: -15.89%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

17.61%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

14.33%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.89%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifestyle Aggressive Growth Fund | Morningstar Aggressive Target Risk Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(8.17%)

5 Years

rr_AverageAnnualReturnYear05

5.01%

Since Inception

rr_AverageAnnualReturnSinceInception

9.03%

^[1]

TIAA-CREF Lifestyle Aggressive Growth Fund | Lifestyle Aggressive Growth Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(8.12%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.74%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

10.06%

^[1],[2]

TIAA-CREF Lifestyle Aggressive Growth Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.18%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.46%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.74%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.56%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 57

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

218

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

394

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 902

Annual Return 2012

rr_AnnualReturn2012

19.18%

Annual Return 2013

rr_AnnualReturn2013

29.87%

Annual Return 2014

rr_AnnualReturn2014

4.51%

Annual Return 2015

rr_AnnualReturn2015

0.28%

Annual Return 2016

rr_AnnualReturn2016

7.55%

Annual Return 2017

rr_AnnualReturn2017

25.58%

Annual Return 2018

rr_AnnualReturn2018

(11.18%)

1 Year

rr_AverageAnnualReturnYear01

(11.18%)

5 Years

rr_AverageAnnualReturnYear05

4.69%

Since Inception

rr_AverageAnnualReturnSinceInception

9.75%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Aggressive Growth Fund | Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(12.33%)

5 Years

rr_AverageAnnualReturnYear05

3.37%

Since Inception

rr_AverageAnnualReturnSinceInception

8.48%

TIAA-CREF Lifestyle Aggressive Growth Fund | Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.82%)

5 Years

rr_AverageAnnualReturnYear05

3.48%

Since Inception

rr_AverageAnnualReturnSinceInception

7.65%

TIAA-CREF Lifestyle Aggressive Growth Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.25%

^[5]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.46%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.81%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.63%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 64

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

241

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

432

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 985

1 Year

rr_AverageAnnualReturnYear01

(11.17%)

5 Years

rr_AverageAnnualReturnYear05

4.66%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

9.73%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifestyle Aggressive Growth Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.18%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.46%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.89%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.18%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.71%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 73

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

266

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

475

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,080

1 Year

rr_AverageAnnualReturnYear01

(11.29%)

5 Years

rr_AverageAnnualReturnYear05

4.54%

Since Inception

rr_AverageAnnualReturnSinceInception

9.59%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Aggressive Growth Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

none

Management fees

rr_ManagementFeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.42%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.46%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.98%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

295

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

525

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,186

1 Year

rr_AverageAnnualReturnYear01

(11.39%)

5 Years

rr_AverageAnnualReturnYear05

4.42%

Since Inception

rr_AverageAnnualReturnSinceInception

9.47%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

TIAA-CREF Lifestyle Aggressive Growth Fund | Retail Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Account maintenance fee (annual fee on accounts under $2,000)

rr_ShareholderFeeOther

$ 15.00

Management fees

rr_ManagementFeesOverAssets

0.10%

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.22%

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.46%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.03%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[4]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.86%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 88

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

311

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

552

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,244

1 Year

rr_AverageAnnualReturnYear01

(11.46%)

5 Years

rr_AverageAnnualReturnYear05

4.35%

Since Inception

rr_AverageAnnualReturnSinceInception

9.39%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 09, 2011

[1] Performance is calculated from the inception date of the Institutional Class.

[2] As of the close of business on December 31, 2018, the Lifestyle Aggressive Growth Fund Composite Index consisted of: 70.0% Russell 3000® Index; and 30.0% MSCI All Country World Index ex USA Investable Market Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[5] Restated to reflect estimate for the current fiscal year.

[6] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2060 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2060 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2060 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 28% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

28.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2060 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 93.75% of the Fund’s assets to equity Underlying Funds and 6.25% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2060 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2090. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 65.62%; International Equity: 28.13%; Fixed-Income: 6.25%; Short-Term Fixed-Income: 0.00%; and Inflation-Protected Assets: 0.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, for June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	94.13%	U.S. Equity	66.01%	ŸEquity Index Fund	66.01%
		International Equity	28.12%	ŸInternational Equity Index Fund	20.16%
				ŸEmerging Markets Equity Index Fund	7.96%
Fixed-Income	5.87%	Fixed-Income	5.87%	ŸBond Index Fund	5.87%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI EAFE + Emerging Markets Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2060 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.05%.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best quarter: 6.23%, for the quarter ended March 31, 2017. Worst quarter: -12.40%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.05%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.23%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(12.40%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2060 Fund | S&P Target Date 2060+ Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.95%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.99%

^[1]

TIAA-CREF Lifecycle Index 2060 Fund | Lifecycle Index 2060 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.35%)

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

5.51%

^[1],[2]

TIAA-CREF Lifecycle Index 2060 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.18%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.33%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.23%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

83

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

162

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 396

1 Year

rr_AverageAnnualReturnYear01

(7.13%)

Since Inception

rr_AverageAnnualReturnSinceInception

5.45%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle Index 2060 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.26%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.41%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.23%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 18

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

108

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

207

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 495

1 Year

rr_AverageAnnualReturnYear01

(7.16%)

Since Inception

rr_AverageAnnualReturnSinceInception

5.36%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2060 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.18%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.48%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.23%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

131

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

246

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 581

1 Year

rr_AverageAnnualReturnYear01

(7.26%)

Since Inception

rr_AverageAnnualReturnSinceInception

5.31%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle Index 2060 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.15%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.43%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.58%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.23%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

163

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

301

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 704

Annual Return 2015

rr_AnnualReturn2015

(0.90%)

Annual Return 2016

rr_AnnualReturn2016

9.55%

Annual Return 2017

rr_AnnualReturn2017

21.61%

Annual Return 2018

rr_AnnualReturn2018

(7.33%)

1 Year

rr_AverageAnnualReturnYear01

(7.33%)

Since Inception

rr_AverageAnnualReturnSinceInception

5.20%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 26, 2014

TIAA-CREF Lifecycle Index 2060 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.91%)

Since Inception

rr_AverageAnnualReturnSinceInception

4.48%

TIAA-CREF Lifecycle Index 2060 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.97%)

Since Inception

rr_AverageAnnualReturnSinceInception

3.93%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2060 Fund Composite Index consisted of: 65.9% Russell 3000® Index; 28.2% MSCI EAFE + Emerging Markets Index; and 5.9% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.06% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.04% of average daily net assets for Institutional Class shares; (ii) 0.19% of average daily net assets for Advisor Class shares; (iii) 0.19% of average daily net assets for Premier Class shares; and (iv) 0.29% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

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TIAA-CREF Lifestyle Growth Fund

TIAA-CREF Lifestyle Growth Fund

Investment objective

The Fund seeks long-term growth of capital with some current income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifestyle Growth Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none	none
Maximum deferred sales charge	none	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none	none
Redemption or exchange fee	none	none	none	none	none
Account maintenance fee (annual fee on accounts under $2,000)	none	none	none	none	$ 15.00

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifestyle Growth Fund		Institutional Class	Advisor Class		Premier Class	Retirement Class	Retail Class
Management fees		0.10%	0.10%		0.10%	0.10%	0.10%
Distribution (Rule 12b-1) fees					0.15%		0.25%
Other expenses		0.13%	0.21%	[1]	0.13%	0.37%	0.15%
Acquired Fund fees and expenses	[2]	0.43%	0.43%		0.43%	0.43%	0.43%
Total annual Fund operating expenses		0.66%	0.74%		0.81%	0.90%	0.93%
Waivers and expense reimbursements	[3]	(0.13%)	(0.13%)		(0.13%)	(0.12%)	(0.12%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.53%	0.63%		0.68%	0.78%	0.81%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the duration noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifestyle Growth Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class	Retail Class
1 year	$ 54	$ 64	$ 69	$ 80	$ 83
3 years	198	226	246	275	284
5 years	355	401	437	487	503
10 years	$ 810	$ 908	$ 990	$ 1,097	$ 1,132

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Institutional Class shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). The Fund is designed for investors seeking long-term growth of capital with some current income through a relatively stable asset allocation strategy targeting a growth-oriented risk-return profile. Advisors generally seeks to meet the Fund’s investment objective by investing: (1) approximately 80% of the Fund’s assets in equity Underlying Funds and (2) approximately 20% of the Fund’s assets in fixed-income Underlying Funds. The Fund may deviate from these target allocations by up to ten percentage points depending upon current market conditions and outlook.

The Underlying Funds’ allocation targets generally represent targets for investments in equity and fixed-income asset classes. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (which may include U.S. equity, international equity, fixed-income and short-term fixed-income) represented by various Underlying Funds. To maintain an appropriate allocation among the Underlying Funds, the portfolio managers monitor the domestic and foreign equity markets, as well as overall financial and economic conditions. The Fund may sometimes be more heavily weighted toward equities or fixed-income than the target allocations, if the portfolio managers believe market conditions warrant. For example, the Fund may increase its holdings in fixed-income Underlying Funds in periods when the portfolio managers believe the equity markets will decline. The market sector allocations and Underlying Fund allocations may also be changed over time by the portfolio managers, including the addition and removal of market sectors and Underlying Funds in which the Fund invests in light of the Fund’s desired level of risk and potential return at a particular time as evaluated by the portfolio managers based on a mix of qualitative and quantitative factors. The portfolio managers may also opportunistically purchase other Funds or other investment pools or investment products, based on the portfolio managers’ evaluation of the market sectors and/or Underlying Funds without prior notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund, market sector or asset class not listed in the chart below, shareholders will receive prior notice of such change.

As a result of its investments in the Underlying Funds, the Fund’s returns will reflect investments in a mix of domestic and foreign equities of companies of various sizes and a variety of domestic and foreign fixed-income instruments of private and governmental issuers of varying maturities and credit qualities.

As part of the Fund’s ability to invest in unaffiliated investment products or pools noted above, the Fund may invest in exchange-traded funds (“ETFs”) and exchange-traded notes (“ETNs”) to gain exposure to various market sectors or securities in order to effect its asset allocation strategy. Additionally, the Fund may use ETFs and ETNs for cash management, hedging or defensive purposes. ETFs and ETNs will be subject to the risks associated with the types of securities or sectors that they track, while ETNs, which are structured as fixed-income obligations, will also be subject to the general risks of fixed-income securities, including credit risk.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector as of June 30, 2019, are listed in the chart below. These allocations may change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	80.45%	U.S. Equity	57.42%	ŸLarge-Cap Growth Fund	14.26%
				ŸLarge-Cap Value Fund	13.80%
				ŸGrowth & Income Fund	12.62%
				ŸQuant Large-Cap Growth Fund	7.32%
				ŸQuant Large-Cap Value Fund	4.17%
				ŸQuant Small-Cap Equity Fund	2.83%
				ŸQuant Small/Mid-Cap Equity Fund	2.42%
		International Equity	23.03%	ŸInternational Equity Fund	6.26%
				ŸInternational Opportunities Fund	5.20%
				ŸQuant International Equity Fund	4.26%
				ŸEmerging Markets Equity Fund	4.11%
				ŸQuant International Small-Cap Equity Fund	3.20%
Fixed-Income	19.55%	Fixed-Income	19.55%	ŸBond Plus Fund	19.55%

Total 100.00% 100.00% 100.00%

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund. Because the Fund targets its investments in a higher percentage of equity Underlying Funds, Equity Underlying Funds Risks are expected to predominate.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Institutional Class of the Fund, before taxes, in each full calendar year since inception of the Institutional Class. Because the expenses vary across share classes, the performance of the Institutional Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Institutional Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Institutional, Advisor, Premier, Retirement and Retail classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Institutional Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Institutional Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE INSTITUTIONAL CLASS SHARES (%)† Lifestyle Growth Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.52%.

Best quarter: 11.87%, for the quarter ended March 31, 2012. Worst quarter: -12.86%, for the quarter ended December 31, 2018.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifestyle Growth Fund		1 Year	5 Years		Since Inception		Inception Date
Institutional Class		(9.22%)	4.42%		8.52%		Dec. 09, 2011
Advisor Class		(9.21%)	4.39%	[1]	8.50%	[1]	Dec. 04, 2015
Premier Class		(9.30%)	4.25%		8.35%		Dec. 09, 2011
Retirement Class		(9.42%)	4.15%		8.25%		Dec. 09, 2011
Retail Class		(9.47%)	4.11%		8.20%		Dec. 09, 2011
After Taxes on Distributions | Institutional Class		(10.40%)	3.20%		7.33%
After Taxes on Distributions and Sale of Fund Shares | Institutional Class		(4.77%)	3.21%		6.56%
Morningstar Moderately Aggressive Target Risk Index (reflects no deductions for fees, expenses or taxes)		(6.74%)	4.60%		7.97%	[2]
Lifestyle Growth Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(6.38%)	5.20%		8.55%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Restated to reflect estimate for the current fiscal year.

[2] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests. These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[3] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses and extraordinary expenses) that exceed: (i) 0.10% of average daily net assets for Institutional Class shares; (ii) 0.25% of average daily net assets for Advisor Class shares; (iii) 0.25% of average daily net assets for Premier Class shares; (iv) 0.35% of average daily net assets for Retirement Class shares; and (v) 0.49% of average daily net assets for Retail Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Institutional Class. The performance for these periods has not been restated to reflect higher expenses of the Advisor Class. If those expenses had been reflected, the performance would have been lower.

[2] Performance is calculated from the inception date of the Institutional Class.

[3] As of the close of business on December 31, 2018, the Lifestyle Growth Fund Composite Index consisted of: 56.0% Russell 3000® Index; 24.0% MSCI All Country World Index ex USA Investable Market Index; and 20.0% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle Index 2015 Fund

TIAA-CREF Lifecycle Index 2015 Fund

Investment objective

The Lifecycle Index 2015 Fund seeks high total return over time through a combination of capital appreciation and income.

Fees and expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - TIAA-CREF Lifecycle Index 2015 Fund	Institutional Class	Advisor Class	Premier Class	Retirement Class
Maximum sales charge imposed on purchases (percentage of offering price)	none	none	none	none
Maximum deferred sales charge	none	none	none	none
Maximum sales charge imposed on reinvested dividends and other distributions	none	none	none	none
Redemption or exchange fee	none	none	none	none
Maximum account fee	none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - TIAA-CREF Lifecycle Index 2015 Fund		Institutional Class	Advisor Class	Premier Class	Retirement Class
Management fees	[1],[2]	0.18%	0.18%	0.18%	0.18%
Distribution (Rule 12b-1) fees				0.15%
Other expenses	[1],[2]	0.05%	0.13%	0.05%	0.30%
Total annual Fund operating expenses		0.23%	0.31%	0.38%	0.48%
Waivers and expense reimbursements	[3],[4]	(0.13%)	(0.13%)	(0.13%)	(0.13%)
Total annual Fund operating expenses after fee waiver and/or expense reimbursement		0.10%	0.18%	0.25%	0.35%

Example

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - TIAA-CREF Lifecycle Index 2015 Fund - USD ($)	Institutional Class	Advisor Class	Premier Class	Retirement Class
1 year	$ 10	$ 18	$ 26	$ 36
3 years	61	87	109	141
5 years	116	161	200	256
10 years	$ 280	$ 381	$ 468	$ 591

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Principal investment strategies

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors who retired in, or planned to retire within a few years of, 2015 and who may have begun taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 45.00% of the Fund’s assets to equity Underlying Funds and 55.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative. The Fund had target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2015 and will reach the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2045. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020 which will change over time, are approximately as follows: U.S. Equity: 31.50%; International Equity: 13.50%; Fixed-Income: 39.00%; Short-Term Fixed-Income: 8.00%; and Inflation-Protected Assets: 8.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	46.75%	U.S. Equity	32.79%	ŸEquity Index Fund	32.79%
		International Equity	13.96%	ŸInternational Equity Index Fund	10.01%
				ŸEmerging Markets Equity Index Fund	3.95%
Fixed-Income	53.25%	Fixed-Income	38.30%	ŸBond Index Fund	38.30%
		Short-Term Fixed-Income	7.46%	ŸShort-Term Bond Index Fund	7.46%
		Inflation- Protected Assets	7.49%	ŸInflation-Linked Bond Fund	7.49%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Principal investment risks

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Past performance

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2015 Fund

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 10.65%.

Best quarter: 8.63%, for the quarter ended September 30, 2010. Worst quarter: -8.09%, for the quarter ended September 30, 2011.

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

Average Annual Returns - TIAA-CREF Lifecycle Index 2015 Fund		1 Year	5 Years		Since Inception		Inception Date
Retirement Class		(3.50%)	3.89%		6.35%		Sep. 30, 2009
Institutional Class		(3.29%)	4.14%		6.61%		Sep. 30, 2009
Advisor Class		(3.31%)	4.04%	[1]	6.43%	[1]	Dec. 04, 2015
Premier Class		(3.45%)	3.98%		6.45%		Sep. 30, 2009
After Taxes on Distributions | Retirement Class		(4.37%)	3.14%		5.70%
After Taxes on Distributions and Sale of Fund Shares | Retirement Class		(1.81%)	2.78%		4.89%
S&P Target Date 2015 Index		(3.67%)	3.79%		6.21%	[2]
Lifecycle Index 2015 Fund Composite Index (reflects no deductions for fees, expenses or taxes)	[3]	(3.36%)	4.21%		6.74%	[2]

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

[1] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[2] Restated to reflect estimates for the current fiscal year.

[3] Advisors has contractually agreed to waive 0.095% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[4] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.005% of average daily net assets for Institutional Class shares; (ii) 0.155% of average daily net assets for Advisor Class shares; (iii) 0.155% of average daily net assets for Premier Class shares; and (iv) 0.255% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[1] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.

[2] Performance is calculated from the inception date of the Retirement Class.

[3] As of the close of business on December 31, 2018, the Lifecycle Index 2015 Fund Composite Index consisted of: 38.7% Bloomberg Barclays U.S. Aggregate Bond Index; 32.5% Russell 3000® Index; 14.0% MSCI EAFE + Emerging Markets Index; 7.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 7.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

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TIAA-CREF Lifecycle 2040 Fund

Risk/Return:

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Risk/Return [Heading]

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TIAA-CREF Lifecycle 2040 Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Lifecycle 2040 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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Sep. 30, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 18% of the average value of its portfolio.

Portfolio Turnover, Rate

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18.00%

Expenses Restated to Reflect Current [Text]

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Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2040 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 81.00% of the Fund’s assets to equity Underlying Funds, 14.00% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2040 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2070. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 56.70%; International Equity: 24.30%; Fixed-Income: 14.00%; Short-Term Fixed-Income: 0.00; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	83.23%	U.S. Equity	58.36%	ŸGrowth & Income Fund	12.22%
				ŸLarge-Cap Growth Fund	11.05%
				ŸLarge-Cap Value Fund	10.71%
				ŸQuant Large-Cap Growth Fund	9.65%
				ŸQuant Large-Cap Value Fund	9.38%
				ŸQuant Small-Cap Equity Fund	3.00%
				ŸQuant Small/Mid-Cap Equity Fund	2.35%
		International Equity	24.87%	ŸQuant International Equity Fund	6.49%
				ŸInternational Equity Fund	5.41%
				ŸInternational Opportunities Fund	5.40%
				ŸEmerging Markets Equity Fund	4.26%
				ŸQuant International Small-Cap Equity Fund	3.31%
Fixed-Income	12.14%	Fixed-Income	12.14%	ŸBond Fund	6.37%
				ŸBond Plus Fund	3.94%
				ŸEmerging Markets Debt Fund	0.83%
				ŸInternational Bond Fund	0.64%
				ŸHigh-Yield Fund	0.36%
Real Estate	4.63%	Direct Real Estate	4.63%	ŸTIAA-CREF Real Property Fund LP	4.63%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

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Principal investment risks

Risk Narrative [Text Block]

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You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

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You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

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Past performance

Performance Narrative [Text Block]

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The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year for the last ten years. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

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As of the close of business on December 31, 2018, the Lifecycle 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI All Country World Index ex USA Investable Market Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

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Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2040 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 15.53%.

Bar Chart Closing [Text Block]

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Best quarter: 17.54%, for the quarter ended June 30, 2009. Worst quarter: -16.45%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.53%

Highest Quarterly Return, Label

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Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.54%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.45%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

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After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

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Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

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AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2040 Fund | S&P Target Date 2040 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.41%)

5 Years

rr_AverageAnnualReturnYear05

4.82%

10 Years

rr_AverageAnnualReturnYear10

9.68%

TIAA-CREF Lifecycle 2040 Fund | Lifecycle 2040 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(6.72%)

^[1]

5 Years

rr_AverageAnnualReturnYear05

5.45%

^[1]

10 Years

rr_AverageAnnualReturnYear10

10.44%

^[1]

TIAA-CREF Lifecycle 2040 Fund | Institutional Class

Risk/Return:

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Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.49%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.55%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.44%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 45

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

143

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

275

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 658

1 Year

rr_AverageAnnualReturnYear01

(8.92%)

5 Years

rr_AverageAnnualReturnYear05

4.79%

10 Years

rr_AverageAnnualReturnYear10

10.39%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 17, 2007

TIAA-CREF Lifecycle 2040 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.49%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.11%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.63%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.52%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 53

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

169

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

319

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 755

1 Year

rr_AverageAnnualReturnYear01

(8.97%)

5 Years

rr_AverageAnnualReturnYear05

4.66%

^[7]

10 Years

rr_AverageAnnualReturnYear10

10.19%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2040 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.49%

^[2],[3]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.70%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.59%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 60

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

191

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

357

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 840

1 Year

rr_AverageAnnualReturnYear01

(9.11%)

5 Years

rr_AverageAnnualReturnYear05

4.62%

10 Years

rr_AverageAnnualReturnYear10

10.22%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle 2040 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.49%

^[2],[3]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[2],[3]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.80%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.11%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.69%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 70

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

223

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

412

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 959

Annual Return 2009

rr_AnnualReturn2009

28.39%

Annual Return 2010

rr_AnnualReturn2010

15.21%

Annual Return 2011

rr_AnnualReturn2011

(3.87%)

Annual Return 2012

rr_AnnualReturn2012

17.37%

Annual Return 2013

rr_AnnualReturn2013

25.85%

Annual Return 2014

rr_AnnualReturn2014

4.38%

Annual Return 2015

rr_AnnualReturn2015

(0.11%)

Annual Return 2016

rr_AnnualReturn2016

7.56%

Annual Return 2017

rr_AnnualReturn2017

22.49%

Annual Return 2018

rr_AnnualReturn2018

(9.17%)

1 Year

rr_AverageAnnualReturnYear01

(9.17%)

5 Years

rr_AverageAnnualReturnYear05

4.53%

10 Years

rr_AverageAnnualReturnYear10

10.11%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 15, 2004

TIAA-CREF Lifecycle 2040 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(10.67%)

5 Years

rr_AverageAnnualReturnYear05

2.95%

10 Years

rr_AverageAnnualReturnYear10

8.86%

TIAA-CREF Lifecycle 2040 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.45%)

5 Years

rr_AverageAnnualReturnYear05

3.30%

10 Years

rr_AverageAnnualReturnYear10

8.13%

[1] As of the close of business on December 31, 2018, the Lifecycle 2040 Fund Composite Index consisted of: 59.1% Russell 3000® Index; 25.3% MSCI All Country World Index ex USA Investable Market Index; and 15.6% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[2] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[3] Restated to reflect estimates for the current fiscal year.

[4] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[5] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor and Premier classes that is prior to their inception dates is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor and Premier classes.

XML

Label

Element

Value

TIAA-CREF Lifecycle 2055 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle 2055 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle 2055 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Sep. 30, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 10% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

10.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

“Acquired Fund fees and expenses” are the Fund’s proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because “Acquired Fund fees and expenses” are included in the chart above, the Fund’s operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund’s annual report.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and in other investment pools or investment products, potentially including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2055 and who may begin taking systematic withdrawals upon retirement.

Advisors currently expects to allocate approximately 92.50% of the Fund’s assets to equity Underlying Funds, 2.50% of its assets to fixed-income Underlying Funds and 5.00% of its assets to direct real estate Underlying Funds. These allocations represent targets for equity, fixed-income and direct real estate asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 45.00% equity/50.00% fixed-income/5.00% direct real estate in the Fund’s target retirement year of 2055 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income/0.00% direct real estate in 2085. Within the equity, fixed-income and direct real estate asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income, inflation-protected assets and direct real estate) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 64.75%; International Equity: 27.75%; Fixed-Income: 2.50%; Short-Term Fixed-Income: 0.00%; Inflation-Protected Assets: 0.00%; and Direct Real Estate: 5.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Growth & Income Fund, Large-Cap Growth Fund, Large-Cap Value Fund, Quant Large-Cap Growth Fund, Quant Large-Cap Value Fund, Quant Small-Cap Equity Fund and Quant Small/Mid-Cap Equity Fund (U.S. Equity); Emerging Markets Equity Fund, International Equity Fund, International Opportunities Fund, Quant International Equity Fund and Quant International Small-Cap Equity Fund (International Equity); Bond Fund, Bond Plus Fund, Emerging Markets Debt Fund, High-Yield Fund and International Bond Fund (Fixed-Income); Money Market Fund and Short-Term Bond Fund (Short-Term Fixed-Income); Inflation-Linked Bond Fund (Inflation-Protected Assets); and Real Property Fund LP (Direct Real Estate). TIAA-CREF Real Property Fund LP is a private fund, which is not available for investment by the general public; it is currently offered exclusively to investment pools or investment products managed by Advisors or its affiliates.

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders, and the portfolio management team may use tactical allocation to take advantage of short to intermediate term opportunities through a combination of positions in Underlying Funds. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	92.85%	U.S. Equity	65.09%	ŸGrowth & Income Fund	13.65%
				ŸLarge-Cap Growth Fund	12.32%
				ŸLarge-Cap Value Fund	11.94%
				ŸQuant Large-Cap Growth Fund	10.76%
				ŸQuant Large-Cap Value Fund	10.46%
				ŸQuant Small-Cap Equity Fund	3.34%
				ŸQuant Small/Mid-Cap Equity Fund	2.62%
		International Equity	27.76%	ŸQuant International Equity Fund	7.25%
				ŸInternational Equity Fund	6.04%
				ŸInternational Opportunities Fund	6.02%
				ŸEmerging Markets Equity Fund	4.75%
				ŸQuant International Small-Cap Equity Fund	3.70%
Fixed-Income	2.55%	Fixed-Income	2.55%	ŸBond Fund	1.34%
				ŸBond Plus Fund	0.83%
				ŸEmerging Markets Debt Fund	0.19%
				ŸInternational Bond Fund	0.13%
				ŸHigh-Yield Fund	0.06%
Real Estate	4.60%	Direct Real Estate	4.60%	ŸTIAA-CREF Real Property Fund LP	4.60%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Direct Real Estate	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%	0.00%
40	65.62%	28.13%	5.00%	1.25%	0.00%	0.00%
35	64.75%	27.75%	5.00%	2.50%	0.00%	0.00%
30	63.87%	27.38%	5.00%	3.75%	0.00%	0.00%
25	63.00%	27.00%	5.00%	5.00%	0.00%	0.00%
20	56.70%	24.30%	5.00%	14.00%	0.00%	0.00%
15	50.40%	21.60%	5.00%	23.00%	0.00%	0.00%
10	44.10%	18.90%	5.00%	28.00%	2.00%	2.00%
5	37.80%	16.20%	5.00%	33.00%	4.00%	4.00%
0	31.50%	13.50%	5.00%	38.00%	6.00%	6.00%
-5	28.00%	12.00%	5.00%	39.00%	8.00%	8.00%
-10	24.50%	10.50%	5.00%	40.00%	10.00%	10.00%
-15	22.75%	9.75%	2.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	0.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	0.00%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	0.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Direct Real Estate Underlying Funds Risks—The risks of investing in direct real estate Underlying Funds include risks specific to their investment strategies, as well as risks related to investing in real estate in general, such as:

·real estate-related investment risk—The risks associated with exposure to direct real estate through investing in investment vehicles managed by Advisors that will primarily invest directly in real estate, which can include declines in real estate values or revenues, uninsured losses at properties, the absence of regulatory oversight of and a secondary market for interests in direct real estate Underlying Funds, a scarcity of interests issued by direct real estate Underlying Funds, making it difficult for the Fund to achieve its target allocation, and illiquidity of interests in direct real estate Underlying Funds.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index that represents the market sectors in which the Fund invests across the equity and fixed-income asset classes. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI All Country World Index ex USA Investable Market Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle 2055 Fund

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 16.40%.

Bar Chart Closing [Text Block]

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Best quarter: 12.82%, for the quarter ended March 31, 2012. Worst quarter: -14.52%, for the quarter ended December 31, 2018.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.40%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

12.82%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.52%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle 2055 Fund | S&P Target Date 2055 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.97%)

5 Years

rr_AverageAnnualReturnYear05

5.07%

Since Inception

rr_AverageAnnualReturnSinceInception

6.82%

^[1]

TIAA-CREF Lifecycle 2055 Fund | Lifecycle 2055 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(7.48%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.65%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

7.40%

^[1],[2]

TIAA-CREF Lifecycle 2055 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.06%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.59%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.14%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

153

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

294

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 704

1 Year

rr_AverageAnnualReturnYear01

(9.86%)

5 Years

rr_AverageAnnualReturnYear05

4.89%

Since Inception

rr_AverageAnnualReturnSinceInception

6.91%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle 2055 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.67%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.14%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.53%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 54

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

179

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

338

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 801

1 Year

rr_AverageAnnualReturnYear01

(9.87%)

5 Years

rr_AverageAnnualReturnYear05

4.79%

^[8]

Since Inception

rr_AverageAnnualReturnSinceInception

6.75%

^[8]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle 2055 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.06%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.74%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.14%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.60%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 61

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

201

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

376

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 885

1 Year

rr_AverageAnnualReturnYear01

(10.10%)

5 Years

rr_AverageAnnualReturnYear05

4.72%

Since Inception

rr_AverageAnnualReturnSinceInception

6.74%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle 2055 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.50%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.31%

^[3],[4]

Acquired Fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[5]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.84%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.14%)

^[6],[7]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

233

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

431

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,004

Annual Return 2012

rr_AnnualReturn2012

17.30%

Annual Return 2013

rr_AnnualReturn2013

25.92%

Annual Return 2014

rr_AnnualReturn2014

4.37%

Annual Return 2015

rr_AnnualReturn2015

(0.13%)

Annual Return 2016

rr_AnnualReturn2016

8.06%

Annual Return 2017

rr_AnnualReturn2017

23.85%

Annual Return 2018

rr_AnnualReturn2018

(10.13%)

1 Year

rr_AverageAnnualReturnYear01

(10.13%)

5 Years

rr_AverageAnnualReturnYear05

4.63%

Since Inception

rr_AverageAnnualReturnSinceInception

6.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2011

TIAA-CREF Lifecycle 2055 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(11.10%)

5 Years

rr_AverageAnnualReturnYear05

3.53%

Since Inception

rr_AverageAnnualReturnSinceInception

5.61%

TIAA-CREF Lifecycle 2055 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.40%)

5 Years

rr_AverageAnnualReturnYear05

3.41%

Since Inception

rr_AverageAnnualReturnSinceInception

5.06%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle 2055 Fund Composite Index consisted of: 65.0% Russell 3000® Index; 27.9% MSCI All Country World Index ex USA Investable Market Index; and 7.1% Bloomberg Barclays U.S. Aggregate Bond Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] "Acquired Fund fees and expenses" are the Fund's proportionate amount of the expenses of any investment companies or pools in which it invests (excluding expenses originally incurred by Class W of the Underlying Funds of the Trust that have been incurred directly by the Fund, which are instead reflected in Management fees and Other expenses). These expenses are not paid directly by Fund shareholders. Instead, Fund shareholders bear these expenses indirectly because they reduce Fund performance. Because "Acquired Fund fees and expenses" are included in the chart above, the Fund's operating expenses here will not correlate with the expenses included in the Financial highlights in this Prospectus and the Fund's annual report.

[6] Advisors has contractually agreed to waive 0.10% of the Fund's Management fee. This waiver will remain in effect through September 30, 2022, unless changed with the approval of the Board of Trustees.

[7] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.00% of average daily net assets for Institutional Class shares; (ii) 0.15% of average daily net assets for Advisor Class shares; (iii) 0.15% of average daily net assets for Premier Class shares; and (iv) 0.25% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[8] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.Performance is calculated from the inception date of the Retirement Class.

XML

Label

Element

Value

TIAA-CREF Lifecycle Index 2030 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

TIAA-CREF Lifecycle Index 2030 Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Lifecycle Index 2030 Fund seeks high total return over time through a combination of capital appreciation and income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. In addition to the fees and expenses described below, investors may be required to pay a commission to a broker-dealer or other financial intermediary on purchases and sales of Institutional Class or Advisor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the fiscal year ended May 31, 2019, the Fund’s portfolio turnover rate was 10% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

10.00%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Restated to reflect estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses, before fee waivers and/or expense reimbursements, remain the same. The example assumes that the Fund’s fee waiver and/or expense reimbursement arrangements will each remain in place for the durations noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that invests in Class W shares of other funds of the Trust and potentially in other investment pools or investment products, including other funds advised by the Fund’s investment adviser, Teachers Advisors, LLC (“Advisors”), or its affiliates (collectively, the “Underlying Funds”). In general, the Fund is designed for investors who have an approximate target retirement year in mind, and the Fund’s investments are adjusted from more aggressive to more conservative over time as the Fund’s target retirement year approaches and for approximately 30 years afterwards. The Fund invests in Underlying Funds according to an asset allocation strategy designed for investors retiring in, or planning to retire within a few years of, 2030 and who may begin taking systematic withdrawals upon retirement. The Fund has a policy of investing at least 80% of its assets (net assets, plus the amount of any borrowings for investment purposes) in Underlying Funds that are managed to seek investment returns that track particular market indices.

Advisors currently expects to allocate approximately 66.00% of the Fund’s assets to equity Underlying Funds and 34.00% of its assets to fixed-income Underlying Funds. These allocations represent targets for equity and fixed-income asset classes. Target allocations will change over time and actual allocations may vary up to ten percentage points from the targets. The target allocations along the investment glidepath, illustrated in the chart below, gradually become more conservative, moving to target allocations of approximately 50.00% equity/50.00% fixed-income in the Fund’s target retirement year of 2030 and reaching the Fund’s final target allocation of approximately 20.00% equity/80.00% fixed-income in 2060. Within the equity and fixed-income asset classes, Advisors allocates the Fund’s investments to particular market sectors (U.S. equity, international equity, fixed-income, short-term fixed-income and inflation-protected assets) represented by various Underlying Funds. These market sector allocations may vary by up to 10% from the Fund’s target market sector allocations. The Fund’s current target market sector allocations for June 30, 2020, which will change over time, are approximately as follows: U.S. Equity: 46.20%; International Equity: 19.80%; Fixed-Income: 30.00%; Short-Term Fixed-Income: 2.00%; and Inflation-Protected Assets: 2.00%. The asset class and market sector names used herein are intended to reflect the primary type of investment of the Underlying Funds within each of these categories.

The Fund’s target market sector allocations to Underlying Funds may include the TIAA-CREF Equity Index Fund (U.S. Equity); Emerging Markets Equity Index Fund and International Equity Index Fund (International Equity); Bond Index Fund (Fixed-Income); Short-Term Bond Index Fund (Short-Term Fixed-Income); and Inflation-Linked Bond Fund (Inflation-Protected Assets).

Additional or replacement Underlying Funds for each market sector, as well as additional or replacement market sectors, may be included when making future allocations if Advisors believes that such Underlying Funds and/or market sectors are appropriate in light of the Fund’s desired levels of risk and potential return at the particular time. The Fund’s portfolio management team may also add a new market sector if it believes that will help to achieve the Fund’s investment objective. The relative allocations among Underlying Funds within a market sector may be changed at any time without notice to shareholders. If 10% or more of the Fund’s assets are expected to be invested in any Underlying Fund or market sector not listed above, shareholders will receive prior notice of such change.

The Fund’s asset class allocations, market sector allocations within each asset class, and Underlying Fund allocations within each market sector, as of June 30, 2019, are listed in the chart below. These allocations will change over time. Underlying Fund allocations in particular may change from year to year.

Asset Class	Allocation	Market Sector	Allocation	Underlying Funds	Allocation
Equity	68.26%	U.S. Equity	47.88%	ŸEquity Index Fund	47.88%
		International Equity	20.38%	ŸInternational Equity Index Fund	14.61%
				ŸEmerging Markets Equity Index Fund	5.77%
Fixed-Income	31.74%	Fixed-Income	28.64%	ŸBond Index Fund	28.64%
		Short-Term Fixed-Income	1.55%	ŸShort-Term Bond Index Fund	1.55%
		Inflation- Protected Assets	1.55%	ŸInflation-Linked Bond Fund	1.55%

Total 100.00% 100.00% 100.00%

The following chart shows how the investment glidepath for the Fund is expected to gradually move the Fund’s target allocations over time between the different target market sector allocations. The actual market sector allocations of the Fund may differ from this chart. The Fund seeks to achieve its final target market sector allocations approximately 30 years following the target date.

Lifecycle Index Funds Glidepath as of June 30, 2020
Years to Target Retirement Date	US Equities	International Equities	Fixed Income	Short Term Fixed Income	Inflation Protected Bonds
45	66.50%	28.50%	5.00%	0.00%	0.00%
40	65.62%	28.13%	6.25%	0.00%	0.00%
35	64.75%	27.75%	7.50%	0.00%	0.00%
30	63.87%	27.38%	8.75%	0.00%	0.00%
25	63.00%	27.00%	10.00%	0.00%	0.00%
20	57.40%	24.60%	18.00%	0.00%	0.00%
15	51.80%	22.20%	26.00%	0.00%	0.00%
10	46.20%	19.80%	30.00%	2.00%	2.00%
5	40.60%	17.40%	34.00%	4.00%	4.00%
0	35.00%	15.00%	38.00%	6.00%	6.00%
-5	31.50%	13.50%	39.00%	8.00%	8.00%
-10	28.00%	12.00%	40.00%	10.00%	10.00%
-15	24.50%	10.50%	40.00%	15.00%	10.00%
-20	21.00%	9.00%	40.00%	20.00%	10.00%
-25	17.50%	7.50%	40.00%	25.00%	10.00%
-30	14.00%	6.00%	40.00%	30.00%	10.00%

The Fund is designed to accommodate investors who invest in a fund up to their target retirement date, and plan to make gradual systematic withdrawals in retirement. In addition, investors should note that the Fund will continue to have a significant level of equity exposure up to, through and after its target retirement date, and this exposure could cause significant fluctuations in the value of the Fund depending on the performance of the equity markets generally.

After the Fund reaches its final target allocation, the Board of Trustees may authorize the merger of the Fund into another Lifecycle Index Fund which has also reached its final target allocation or other similar fund designed to maintain a relatively stable asset allocation reflecting the resting point on the glidepath described in the chart above. Fund shareholders will receive prior notice of any such merger.

Risk [Heading]

rr_RiskHeading

Principal investment risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money over short or long periods by investing in this Fund. An investment in the Fund, due to the nature of the Fund’s portfolio holdings, typically is subject to the following principal investment risks:

·Asset Allocation Risk—The risk that the Fund may not achieve its target allocations. In addition, there is the risk that the asset allocations may not achieve the desired risk-return characteristic or that the selection of Underlying Funds and the allocations among them will result in the Fund underperforming other similar funds or cause an investor to lose money.

·Index Risk—The risk that the Fund’s performance may not correspond to its benchmark index for any period of time and may underperform such index or the overall financial market. Additionally, to the extent that the Fund’s investments vary from the composition of its benchmark index, the Fund’s performance could potentially vary from the index’s performance to a greater extent than if the Fund merely attempted to replicate the index.

·Underlying Funds Risks—The Fund is exposed to the risks of the Underlying Funds in which it invests in direct proportion to the amount of assets the Fund allocates to each Underlying Fund.

·Equity Underlying Funds Risks—The risks of investing in equity Underlying Funds include risks specific to their investment strategies, as well as risks related to the equity markets in general, such as:

·market risk—The risk that the price of equity investments may decline in response to general market and economic conditions or events, including conditions and developments outside of the financial markets;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time; and

·foreign investment risk—The increased risks of adverse issuer, political, regulatory, currency, market or economic developments compared to investments in U.S. issuers, which can result in greater market and price volatility.

·Fixed-Income Underlying Funds Risks—The risks of investing in fixed-income Underlying Funds include risks specific to their investment strategies, as well as risks related to the fixed-income markets in general, such as:

·interest rate risk—The risk that the value or yield of fixed-income investments may decline if interest rates change, which could adversely affect a Fund’s income or the value of its holdings;

·extension risk—The risk that during periods of rising interest rates, borrowers may pay off their mortgage loans later than expected, preventing a Fund from reinvesting principal proceeds at higher interest rates and resulting in less income than potentially available;

·issuer risk—The risk that an issuer’s earnings prospects and overall financial position will deteriorate, causing a decline in the value of the issuer’s financial instruments over short or extended periods of time;

·credit risk—The risk that a decline in an issuer’s financial position may prevent it from making principal and interest payments on fixed-income investments held by a Fund when due;

·credit spread risk—The risk that credit spreads (i.e., the difference in yield between securities that is due to differences in each security’s respective credit quality) may increase when market participants believe that bonds generally have a greater risk of default, which could result in a decline in the market values of a Fund’s debt securities;

·income volatility risk—The risk that the level of current income from a Fund’s portfolio of fixed-income securities may decline due to rapid and unpredictable changes in prevailing market interest rates; and

·call risk—The risk that, during periods of falling interest rates, an issuer may call (or repay) a fixed-income security prior to maturity, resulting in a decline in a Fund’s income.

·Active Management Risk—The risk that the strategy, investment selection or trading execution of Advisors could cause the Fund or an Underlying Fund to underperform its benchmark index or mutual funds with similar investment objectives.

·Fund of Funds Risk—The ability of the Fund to achieve its investment objective will depend in part upon the ability of the Underlying Funds to achieve their investment objectives. There can be no guarantee that any Underlying Fund will achieve its investment objective.

There can be no assurances that the Fund will achieve its investment objective. You should not consider the Fund to be a complete investment program. Please see the non-summary portion of the Prospectus for more detailed information about the risks described above, including the risks of the Underlying Funds.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money over short or long periods by investing in this Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year. The bar chart shows the annual total returns of the Retirement Class of the Fund, before taxes, in each full calendar year since inception of the Retirement Class. Because the expenses vary across share classes, the performance of the Retirement Class may vary from the other share classes. Below the bar chart are the best and worst returns of the Retirement Class for a calendar quarter during the full calendar-year periods covered by the bar chart. The performance table following the bar chart shows the Fund’s average annual total returns for the Retirement, Institutional, Advisor and Premier classes over the applicable one-year, five-year, ten-year and since-inception periods ended December 31, 2018, and how those returns compare to those of a broad-based securities market index and a composite index based on the Fund’s target allocations. After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

The returns shown below reflect previous agreements by Advisors to waive or reimburse the Fund and certain Underlying Funds for certain fees and expenses. Without these waivers and reimbursements, the returns of the Fund would have been lower. Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future. The indices listed below are unmanaged, and you cannot invest directly in an index. The returns for the indices reflect no deduction for fees, expenses or taxes.

For current performance information of each share class, including performance to the most recent month-end, please visit www.tiaa.org.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following chart and table help illustrate some of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

As of the close of business on December 31, 2018, the Lifecycle Index 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI EAFE + Emerging Markets Index; 1.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund’s composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark’s performance may vary over time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.tiaa.org

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance of the Fund (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURNS FOR THE RETIREMENT CLASS SHARES (%)† Lifecycle Index 2030 Fund

Bar Chart Footnotes [Text Block]

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^†The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was 13.26%.

Bar Chart Closing [Text Block]

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Best quarter: 11.08%, for the quarter ended September 30, 2010. Worst quarter: -12.86%, for the quarter ended September 30, 2011.

Year to Date Return, Label

rr_YearToDateReturnLabel

The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2019, was

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

13.26%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.08%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(12.86%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deductions for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs).

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for the Retirement Class shares, and after-tax returns for the other classes of shares will vary from the after-tax returns presented for Retirement Class shares.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Current performance of the Fund’s shares may be higher or lower than that shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect during the periods shown and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(a), 401(k) or 403(b) plans or Individual Retirement Accounts (IRAs). After-tax returns are shown for only one class, and after-tax returns for other classes will vary.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURNS For the Periods Ended December 31, 2018

TIAA-CREF Lifecycle Index 2030 Fund | S&P Target Date 2030 Index

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.99%)

5 Years

rr_AverageAnnualReturnYear05

4.50%

Since Inception

rr_AverageAnnualReturnSinceInception

7.71%

^[1]

TIAA-CREF Lifecycle Index 2030 Fund | Lifecycle Index 2030 Fund Composite Index (reflects no deductions for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.17%)

^[2]

5 Years

rr_AverageAnnualReturnYear05

5.04%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

8.28%

^[1],[2]

TIAA-CREF Lifecycle Index 2030 Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.20%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 10

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

54

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

103

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 245

1 Year

rr_AverageAnnualReturnYear01

(5.04%)

5 Years

rr_AverageAnnualReturnYear05

4.97%

Since Inception

rr_AverageAnnualReturnSinceInception

8.17%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2030 Fund | Advisor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.29%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 19

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

83

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

153

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 358

1 Year

rr_AverageAnnualReturnYear01

(5.14%)

5 Years

rr_AverageAnnualReturnYear05

4.82%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

7.96%

^[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 04, 2015

TIAA-CREF Lifecycle Index 2030 Fund | Premier Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Distribution (Rule 12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.15%

Other expenses

rr_OtherExpensesOverAssets

0.03%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.35%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

102

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

186

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 433

1 Year

rr_AverageAnnualReturnYear01

(5.21%)

5 Years

rr_AverageAnnualReturnYear05

4.82%

Since Inception

rr_AverageAnnualReturnSinceInception

8.01%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2030 Fund | Retirement Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge imposed on purchases (percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum sales charge imposed on reinvested dividends and other distributions

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption or exchange fee

rr_RedemptionFeeOverRedemption

none

Maximum account fee

rr_MaximumAccountFeeOverAssets

none

Management fees

rr_ManagementFeesOverAssets

0.17%

^[3],[4]

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[3],[4]

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.45%

Waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[5],[6]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

134

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

242

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 557

Annual Return 2010

rr_AnnualReturn2010

12.91%

Annual Return 2011

rr_AnnualReturn2011

(0.53%)

Annual Return 2012

rr_AnnualReturn2012

13.98%

Annual Return 2013

rr_AnnualReturn2013

20.63%

Annual Return 2014

rr_AnnualReturn2014

6.41%

Annual Return 2015

rr_AnnualReturn2015

(0.61%)

Annual Return 2016

rr_AnnualReturn2016

7.62%

Annual Return 2017

rr_AnnualReturn2017

16.74%

Annual Return 2018

rr_AnnualReturn2018

(5.27%)

1 Year

rr_AverageAnnualReturnYear01

(5.27%)

5 Years

rr_AverageAnnualReturnYear05

4.71%

Since Inception

rr_AverageAnnualReturnSinceInception

7.90%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2009

TIAA-CREF Lifecycle Index 2030 Fund | Retirement Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(5.91%)

5 Years

rr_AverageAnnualReturnYear05

4.06%

Since Inception

rr_AverageAnnualReturnSinceInception

7.34%

TIAA-CREF Lifecycle Index 2030 Fund | Retirement Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(2.85%)

5 Years

rr_AverageAnnualReturnYear05

3.51%

Since Inception

rr_AverageAnnualReturnSinceInception

6.28%

[1] Performance is calculated from the inception date of the Retirement Class.

[2] As of the close of business on December 31, 2018, the Lifecycle Index 2030 Fund Composite Index consisted of: 47.9% Russell 3000® Index; 28.8% Bloomberg Barclays U.S. Aggregate Bond Index; 20.5% MSCI EAFE + Emerging Markets Index; 1.4% Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index; and 1.4% Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) 1-10 Year Index. The Fund's composite benchmark, the components that make up a composite benchmark and the method of calculating a composite benchmark's performance may vary over time.

[3] Portions of the Management fees and Other expenses are based on expenses originally incurred by Class W shares of the Underlying Funds (as defined below) of the Trust, which have been incurred directly by the Fund pursuant to certain contractual arrangements intended to reallocate directly to the Fund certain fees and expenses that had been paid by the Underlying Funds of the Trust. For additional information, please see the "Management of the Funds" section of this Prospectus.

[4] Restated to reflect estimates for the current fiscal year.

[5] Advisors has contractually agreed to waive 0.075% of the Fund's Management fee. This waiver will remain in effect through September 30, 2020, unless changed with the approval of the Board of Trustees.

[6] Under the Fund's expense reimbursement arrangements, the Fund's investment adviser, Teachers Advisors, LLC ("Advisors"), has contractually agreed to reimburse the Fund for any Total annual Fund operating expenses (excluding interest, taxes, brokerage commissions or other transactional expenses, Acquired Fund fees and expenses, extraordinary expenses and any expenses originally attributable to Class W shares of the Underlying Funds of the Trust that were incurred directly by the Fund) that exceed: (i) 0.025% of average daily net assets for Institutional Class shares; (ii) 0.175% of average daily net assets for Advisor Class shares; (iii) 0.175% of average daily net assets for Premier Class shares; and (iv) 0.275% of average daily net assets for Retirement Class shares of the Fund. These expense reimbursement arrangements will continue through at least September 30, 2020, unless changed with approval of the Board of Trustees.

[7] The performance shown for the Advisor Class that is prior to its inception date is based on performance of the Fund's Retirement Class. The performance for these periods has not been restated to reflect the lower expenses of the Advisor Class.