485BPOS

Registration No. 33-59474 

U.S. SECURITIES AND EXCHANGE COMMISSION 

WASHINGTON, D. C. 20549

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POST-EFFECTIVE AMENDMENT NO. 115 TO 

FORM N-1A

REGISTRATION STATEMENT

under

THE SECURITIES ACT OF 1933

and

REGISTRATION STATEMENT

under

THE INVESTMENT COMPANY ACT OF 1940 

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PRINCIPAL FUNDS, INC.

(Exact name of Registrant as specified in Charter) 

The Principal Financial Group

Des Moines, Iowa 50392

(Address of principal executive offices)

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Telephone Number (515) 248-3842

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	Copy to:
MICHAEL D. ROUGHTON	JOHN W. BLOUCH, Esq.
The Principal Financial Group	Drinker Biddle & Reath, LLP
Des Moines, Iowa 50392	1500 K Street, N.W.
	Washington, DC 20005-1209

(Name and address of agent for service)
----------
It is proposed that this filing will become effective (check appropriate box)
__XX___	immediately upon filing pursuant to paragraph (b) of Rule 485
______	on (date), pursuant to paragraph (b) of Rule 485
______	60 days after filing pursuant to paragraph (a)(1) of Rule 485
______	on (date) pursuant to paragraph (a)(1) of Rule 485
______	75 days after filing pursuant to paragraph (a)(2) of Rule 485
______	on (date) pursuant to paragraph (a)(2) of Rule 485
If appropriate, check the following box:)
	This post-effective amendment designates a new effective date for a previously filed post-effective
	amendment.
	Explanatory Note:
This filing relates to the Series and share classes in the Registrant's Class A and Class C prospectus, Class
J prospectus, and Institutional Class prospectus, each dated June 13, 2012 (as filed on June 13, 2012, SEC
Accession No. 0001144204-12-034634), and is filed for the purpose of submitting interactive data files.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the 

Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to the 

Registration Statement on Form N-1A, pursuant to Rule 485(b) under the Securities Act of 1933, and has 

duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, 

thereto duly authorized in the City of Des Moines and State of Iowa, on the 27^th day of June, 2012. 

Principal Funds, Inc. 

       (Registrant) 

              /s/ N. M. Everett 

N. M. Everett 

President, Chief Executive Officer 

and Director 

Attest: 

/s/ Beth Wilson 

Beth Wilson 

Vice President and Secretary 

Pursuant to the requirements of the Securities Act of 1933, this Amendment to the Registration Statement
has been signed below by the following persons in the capacities and on the dates indicated.
Signature	Title	Date
______________________________	Chairman of the Board	June 27, 2012
R. C. Eucher
/s/ N. M. Everett
______________________________	President, Chief Executive	June 27, 2012
N. M. Everett	Officer and Director (Principal
	Executive Officer)
/s/ L. A. Rasmussen
______________________________	Vice President, Controller and	June 27, 2012
L. A. Rasmussen	Chief Financial Office (Principal
	Financial Officer and Controller)
/s/ M. J. Beer
______________________________	Executive Vice President	June 27, 2012
M. J. Beer	and Director
(E. Ballantine)*
______________________________	Director	June 27, 2012
E. Ballantine
(L. T. Barnes)*
______________________________	Director	June 27, 2012
L. T. Barnes
(K. Blake)*
______________________________	Director	June 27, 2012
K. Blake
(C. Damos)*
______________________________	Director	June 27, 2012
C. Damos
(R. W. Gilbert)*
______________________________	Director	June 27, 2012
R. W. Gilbert
(M. A. Grimmett)*
______________________________	Director	June 27, 2012
M. A. Grimmett
(F. S. Hirsch)*
______________________________	Director	June 27, 2012
F. S. Hirsch
(T. Huang)*
______________________________	Director	June 27, 2012
T. Huang

(W. C. Kimball)*
______________________________	Director	June 27, 2012
W. C. Kimball
(B. A. Lukavsky)*
______________________________	Director	June 27, 2012
B. A. Lukavsky
(D. Pavelich)*
______________________________	Director	June 27, 2012
D. Pavelich

	/s/ M. J. Beer
By	______________________________
	M. J. Beer
	Executive Vice President and Director
*	Pursuant to Powers of Attorney
	Previously filed

Exhibit No.	Exhibits
Ex-101.INS	XBRL Instance Document
Ex-101.SCH	XBRL Taxonomy Extension Schema Document
Ex-101.CAL	XBRL Taxonomy Extension Calculations Linkbase Document
Ex-101.DEF	XBRL Taxonomy Extension Definition Linkbase Document
Ex-101.LAB	XBRL Taxonomy Extension Labels Linkbase Document
Ex-101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Blue Chip Fund (Prospectus Summary) | Blue Chip Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Blue Chip Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund seeks long-term growth of capital.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment): None
Operating Expenses, Caption	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	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. This is a new Fund and does not yet have a portfolio turnover rate to disclose.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated for the year ending August 31, 2012.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in equity securities of companies with large market capitalizations (those with market capitalizations similar to companies in the Russell 1000 Growth® Index (as of December 31, 2011, this range was between approximately $578 million and $401.25 billion) at the time of purchase. The Fund may invest in foreign securities.    The Fund invests in growth equity securities; growth orientation emphasizes buying equity securities of companies whose potential for growth of capital and earnings is expected to be above average.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors seeking long-term growth of capital and willing to accept the potential for short-term fluctuations in the value of investments. The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are: Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies. Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; changes in foreign exchange rates and foreign exchange restrictions; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies).    Growth Stock Risk. If growth companies do not increase their earnings at a rate expected by investors, the market price of the stock may decline significantly, even if earnings show an absolute increase. Growth company stocks also typically lack the dividend yield that can lessen price declines in market downturns.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance information is shown because the Fund has not yet had a calendar year of performance. The Fund's performance will be benchmarked against the Russell 1000 Growth Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance information is shown because the Fund has not yet had a calendar year of performance.
Blue Chip Fund (Prospectus Summary) | Blue Chip Fund | Institutional Class
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.70%
Other Expenses	rr_OtherExpensesOverAssets	0.51%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.21%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.46%)	[2]
Total Annual Fund Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.75%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	77
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	339

[1] Other Expenses are estimated for the year ending August 31, 2012.

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Institutional class shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 0.75%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

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Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund

Preferred Securities Fund

Objective:

The Fund seeks to provide current income.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Preferred Securities Fund Class J
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Preferred Securities Fund Class J
Management Fees		0.71%
Distribution and/or Service (12b-1) Fees		0.45%
Other Expenses	[1]	0.34%
Total Annual Fund Operating Expenses		1.50%
Fee Waiver	[2]	0.20%
Total Annual Fund Operating Expenses After Fee Waiver		1.30%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years	Expense Example, With Redemption, 5 Years	Expense Example, With Redemption, 10 Years
Preferred Securities Fund Class J	232	454	800	1,773

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years	Expense Example, No Redemption, 5 Years	Expense Example, No Redemption, 10 Years
Preferred Securities Fund Class J	132	454	800	1,773

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 most recent fiscal year, the Fund's annualized portfolio turnover
rate was 16.8% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets,
plus borrowings for investment purposes, in preferred securities at the time
of purchase. Preferred securities generally pay fixed rate dividends (though
some are adjustable rate) and typically have "preference" over common stock in
the payment of dividends and the liquidation of a company's assets, but are junior
to all forms of the company's debt. Most of the securities purchased by the Fund
are preferred securities of companies rated at the time of purchase BBB- or higher
by Standard & Poor's Rating Service ("S&P") or Baa3 or higher by Moody's Investor
Service, Inc. ("Moody's") or, if unrated, of comparable quality in the opinion of
the Sub-Advisor. The Fund also invests up to 15% of its assets in high yield, below
investment grade quality debt (sometimes called "junk bonds" and rated at the time
of purchase BB+ or lower by S&P or rated Ba1 or lower by Moody's or of equivalent
quality as determined by the Sub-Advisor).
  
The Fund will concentrate its investments (invest more than 25% of its net assets)
in securities in the U.S. and non-U.S financial services (i.e., banking, insurance
and commercial finance,) industry. The Fund also regularly invests in the real estate
investment trust (i.e. REIT) and utility industries.

Principal Risks

Principal Risks The Fund may be an appropriate investment for investors who are
seeking dividends to generate income or to reinvest for growth and are willing
to accept fluctuations in the value of the investment.
  
The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:
  
Equity Securities Risk. Equity securities (common, convertible preferred stocks
and other securities whose values are tied to the price of stocks, such as rights,
warrants and convertible debt securities) could decline in value if the issuer's
financial condition declines or in response to overall market and economic conditions.
A fund's principal market segment(s), such as large cap, mid cap or small cap stocks,
or growth or value stocks, may underperform other market segments or the equity
markets as a whole. Investments in smaller companies and mid-size companies may
involve greater risk and price volatility than investments in larger, more mature
companies.
  
Fixed-Income Securities Risk. Fixed-income securities are subject to interest
rate risk and credit quality risk. The market value of fixed-income securities
generally declines when interest rates rise, and an issuer of fixed-income
securities could default on its payment obligations.

Foreign Securities Risk. The risks of foreign securities include loss of value
as a result of: political or economic instability; nationalization, expropriation
or confiscatory taxation; changes in foreign exchange rates and foreign exchange
restrictions; settlement delays; and limited government regulation (including
less stringent reporting, accounting, and disclosure standards than are required
of U.S. companies).
  
High Yield Securities Risk. High yield fixed-income securities (commonly
referred to as "junk bonds") are subject to greater credit quality risk than
higher rated fixed-income securities and should be considered speculative.
  
Industry Concentration Risk. A fund that concentrates investments in a
particular industry or group of industries (e.g., energy, real estate,
technology, financial services) has greater exposure than other funds to
market, economic and other factors affecting that industry.
  
Portfolio Duration Risk. Portfolio duration is a measure of the expected life
of a fixed-income security and its sensitivity to changes in interest rates. The
longer a fund's average portfolio duration, the more sensitive the fund will be
to changes in interest rates.
  
Preferred Securities Risk. Preferred securities are junior subordinated
securities in a company's capital structure and therefore can be subject to
greater credit and liquidation risk. An issuer of preferred securities could
redeem the security prior to the stated maturity date and reduce the return of
the security.
  
Real Estate Investment Trusts ("REITs") Risk. A REIT could fail to qualify for
tax-free pass-through of income under the Internal Revenue Code, and fund
shareholders will indirectly bear their proportionate share of the expenses of
REITs in which the fund invests.
  
Real Estate Securities Risk. Real estate securities are subject to the risks
associated with direct ownership of real estate, including declines in value,
adverse economic conditions, increases in expenses, regulatory changes and
environmental problems.

Risk of Being an Underlying Fund. An underlying fund of a fund of funds may
experience relatively large redemptions or investments as the fund of funds
periodically reallocates or rebalances its assets. These transactions may cause
the underlying fund to sell portfolio securities to meet such redemptions, or to
invest cash from such investments, at times it would not otherwise do so, and
may as a result increase transaction costs and adversely affect underlying fund
performance.

Performance

The following information provides an indication of the risks of investing in
the Fund. The bar chart shows the investment returns of the Fund's Class J
shares for each full calendar year of operations for 10 years (or, if shorter,
the life of the Fund). These annual returns do not reflect sales charges; if
they did, returns would be lower. The table shows, for Class J shares of the
Fund and for the last one, five, and ten calendar year periods (or, if shorter,
the life of the Fund), how the Fund's average annual total returns compare to
the returns of one or more broad-based market indices. Past performance (before
and after taxes) is not necessarily an indication of how the Fund will perform
in the future. You may get updated performance information online at
www.principalfunds.com or by calling 1-800-222-5852.
  
Class J shares were first sold on December 29, 2003. The returns for the periods
prior to that date are based on the performance of the Institutional Class
shares adjusted to reflect the fees and expenses of Class J shares. The
adjustments result in performance for such periods that is no higher than the
historical performance of the Institutional Class shares. The Institutional
Class shares were first sold on May 1, 2002.
  
Performance of a blended index shows how the Fund's performance compares to
an index with similar investment objectives. Performance of the components of the
blended index are also shown. The weightings for the Preferreds Blended Index
in the Average Annual Total Returns table are 50% BofA Merrill Lynch Fixed Rate
Preferred Securities and 50% Barclays Capital U.S. Tier I Capital Securities
Index. The custom or blended index returns reflect the allocation in effect for
the time period(s) for which fund returns are disclosed. Previous weightings or
allocations of the custom or blended index are not restated.

Total Returns as of December 31 each year (Class J shares)

^[1]

Highest return for a quarter during the period of the bar     Q2 '09      38.56%
chart above:                                                           
Lowest return for a quarter during the period of the bar      Q3 '08     -21.11%
chart above:

Average Annual Total Returns For the periods ended December 31, 2011

Average Annual Total Returns Preferred Securities Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, Since Inception
Class J	Class J Return Before Taxes	0.04%	3.67%	4.41%
Class J After Taxes on Distributions	Class J Return After Taxes on Distributions	(1.80%)	1.66%	2.68%
Class J After Taxes on Distributions and Sales	Class J Return After Taxes on Distribution and Sale of Fund Shares	0.35%	2.00%	2.80%
BofA Merrill Lynch Fixed Rate Preferred Securities Index	BofA Merrill Lynch Fixed Rate Preferred Securities Index (reflects no deduction for fees, expenses, or taxes)	4.11%	(1.19%)	2.42%
Barclays Capital U.S. Tier I Capital Securities Index	Barclays Capital U.S. Tier I Capital Securities Index (reflects no deduction for fees, expenses, or taxes)	(0.53%)	1.71%	4.87%
Preferreds Blended Index	Preferreds Blended Index (reflects no deduction for fees, expenses, or taxes)	1.81%	0.01%	3.38%

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of state and local taxes.
Actual after-tax returns depend on an 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(k) plans or
individual retirement accounts.

[1] Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.

[2] Effective January 1, 2012, Principal Funds Distributor, Inc. ("the Distributor") has contractually agreed to limit the Distribution Fees attributable to Class J through December 31, 2012. The limit will maintain the level of Distribution Fees not to exceed 0.25%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and the Distributor, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

[1] The year-to-date return as of March 31, 2012 was 7.79% for Class J shares.

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Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund

Opportunistic Municipal Fund

Objective:

The Fund seeks to provide a high level of income that is exempt from federal income
tax while protecting investors' capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund. You may qualify for sales charge discounts if you and your
family invest, or agree to invest in the future, at least $100,000 in Principal
Funds, Inc. More information about these and other discounts is available from
your financial professional and in "Choosing a Share Class and The Costs of
Investing" beginning on page 38 of the Fund's prospectus and "Multiple Class
Structure" beginning on page 59 of the Fund's Statement of Additional
Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Opportunistic Municipal Fund	Class A	Class C
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.75%	none
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	1.00%	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Opportunistic Municipal Fund		Class A	Class C
Management Fees		0.50%	0.50%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%
Other Expenses	[1][2]	0.51%	0.54%
Total Annual Fund Operating Expenses		1.26%	2.04%
Expense Reimbursement	[3]	0.29%	0.32%
Total Annual Fund Operating Expenses after Expense Reimbursement		0.97%	1.72%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

Expense Example Opportunistic Municipal Fund (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Class A	470	732
Class C	275	609

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption Opportunistic Municipal Fund (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years
Class A	470	732
Class C	175	609

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.
This is a new Fund and does not yet have a portfolio turnover rate to disclose.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets,
plus borrowings for investment purposes, in municipal obligations (securities
issued by or on behalf of state or local governments and other public
authorities). Municipal obligations pay interest that is exempt from federal
income tax. The Fund has a flexible investment strategy and may invest in
obligations of any duration and credit quality, including below investment grade
bonds (rated at the time of purchase Ba1 or lower by Moody's or BB+ or lower by
S&P, sometimes called "junk bonds") as rated by at least one independent rating
agency, or if unrated, judged to be of comparable quality by the Fund's
Sub-Advisor.

The Fund may invest in other debt obligations, including (but not limited to)
taxable municipal obligations, U.S. Treasury securities, obligations of the U.S.
Government, its agencies and instrumentalities ("Agency Securities") and inverse
floating rate obligations, which are generally more volatile than other types of
municipal obligations. The Fund may invest in exchange-traded funds (ETFs) to
gain exposure to the municipal market.

The Fund may purchase derivative instruments, which derive their value from
another instrument, security or index. The Fund may purchase or sell various
kinds of financial futures contracts to hedge against changes in interest rates
or as a substitute for the purchase of portfolio securities. The Fund also may
enter into interest rate swaps and credit derivatives, which may include credit
default swaps.

Principal Risks

The Fund may be an appropriate investment for investors who are seeking monthly,
federally tax-exempt dividends to produce income or to reinvest for modest
growth and are willing to accept fluctuations in the value of their investment.

The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:
  
Counterparty Risk. Counterparty risk is the risk that the counterparty to a
derivatives contract or repurchase agreement, the borrower of a portfolio's
securities, or other obligation, will be unable or unwilling to make timely
principal, interest, or settlement payments, or otherwise to honor its
obligations.
  
Derivatives Risk. Transactions in derivatives (such as options, futures,
currency contracts, and swaps) may increase volatility, cause the liquidation of
portfolio positions when not advantageous to do so and produce disproportionate
losses.

Exchange-Traded Funds ("ETFs") Risk. An ETF is subject to the risks associated
with direct ownership of the securities comprising the index on which the ETF is
based. Fund shareholders indirectly bear their proportionate share of the
expenses of the ETFs in which the fund invests.
  
Fixed-Income Securities Risk. Fixed-income securities are subject to interest
rate risk and credit quality risk. The market value of fixed-income securities
generally declines when interest rates rise, and an issuer of fixed-income
securities could default on its payment obligations.
  
High Yield Securities Risk. High yield fixed-income securities (commonly
referred to as "junk bonds") are subject to greater credit quality risk than
higher rated fixed-income securities and should be considered speculative.
  
Inverse Floating Rate Investments. Inverse floating rate investments are
extremely sensitive to changes in interest rates and in some cases their market
value may be extremely volatile.

Leverage Risk. Leverage created by borrowing or certain types of transactions or
investments, such as reverse repurchase agreements, loans of portfolio securities,
and the use of when-issued, delayed delivery or forward commitment transactions,
or derivative instruments, may impair the fund's liquidity, cause it to liquidate
positions at an unfavorable time, increase volatility of the fund's net asset value,
or diminish the fund's performance.
  
Municipal Securities Risk. Principal and interest payments on municipal
securities may not be guaranteed by the issuing body and may be payable only
from a particular source. That source may not perform as expected and payment
obligations may not be made or made on time.
  
Portfolio Duration Risk. Portfolio duration is a measure of the expected life of
a fixed-income security and its sensitivity to changes in interest rates. The
longer a fund's average portfolio duration, the more sensitive the fund will be
to changes in interest rates.

U.S. Government Securities Risk. Yields available from U.S. government
securities are generally lower than yields from many other fixed-income
securities.
  
U.S. Government Sponsored Securities Risk. Securities issued by U.S.
government-sponsored or -chartered enterprises such as the Federal Home Loan
Mortgage Corporation, the Federal National Mortgage Association, and the Federal
Home Loan Banks are not issued or guaranteed by the U.S. Treasury.

Performance

No performance information is shown because the Fund has not yet had a calendar
year of performance. The Fund's performance will be benchmarked against the
Barclays Capital Municipal Bond Index.

[1] Other Expenses are estimated for the year ending August 31, 2012.

[2] Other Expenses include: Interest Expense 0.07%

[3] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class A and Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 0.90% for Class A and 1.65% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

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Global Multi-Strategy Fund (Prospectus Summary) | Global Multi-Strategy Fund

Global Multi-Strategy Fund

Objective:

The Fund seeks to achieve long-term capital appreciation with an emphasis on positive
total returns and relatively low volatility.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund. Information about discounts is available from your financial
professional and in "Choosing a Share Class and The Costs of Investing" beginning
on page 38 of the Fund's prospectus and "Multiple Class Structure" beginning on
page 59 of the Fund's Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Global Multi-Strategy Fund Class C
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Global Multi-Strategy Fund Class C
Management Fees		1.60%
Distribution and/or Service (12b-1) Fees		1.00%
Dividend and Interest Expense on Short Sales	[1]	1.56%
Remainder of Other Expenses	[1]	0.45%
Total Annual Fund Operating Expenses		4.61%
Expense Reimbursement	[2]	0.30%
Total Annual Fund Operating Expenses after Expense Reimbursement		4.31%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may
be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Global Multi-Strategy Fund Class C	532	1,364

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years
Global Multi-Strategy Fund Class C	432	1,364

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.
This is a new Fund and does not yet have a portfolio turnover rate to disclose.

Principal Investment Strategies

Principal Management Corporation ("Principal"), the Fund's investment adviser,
allocates the Fund's assets among one or more of the investment strategies
described below, which are executed by one or more of the Fund's sub-advisors.
In making these allocations, Principal seeks to combine the strategies of the
sub-advisors efficiently and systematically so that the Fund generates, through
a diversified set of investment strategies, a positive total return with
relatively low volatility and low sensitivity or correlation to market indices.
By allocating the Fund's assets among a variety of investment strategies, which
will vary from time-to-time, the Fund seeks to lessen risk and reduce volatility.
Principal may also direct a sub-advisor to reduce or omit its investment in certain
assets or asset classes in an effort to achieve its desired combination of the
Fund's strategies.

In pursuing its strategies, the Fund invests in a broad range of instruments
including, but not limited to, equities, bonds, currencies, convertible
securities and derivatives such as futures, options, swaps (including, for
example, credit default, interest rate, and currency swaps) and forwards. The
Fund intends to engage in many derivative transactions to gain exposure to a
variety of securities or attempt to reduce risk. The Fund intends to invest in
securities that are tied economically to a number of countries throughout the
world, including the U.S.; however, the Fund has no requirements as to the
amount of its net assets that it invests in foreign securities. The Fund is
considered non-diversified, which means it can invest a higher percentage of
assets in securities of individual issuers than a diversified fund. The Fund
may actively trade securities.
  
Some of the strategies take long and/or short positions. When taking a short
position, the Fund may sell an instrument that it does not own and then borrow
to meet its settlement obligations. The Fund may take short positions in
futures, forwards or swaps. A short position will benefit from a decrease in
price of the underlying instrument and will lose value if the price of the
underlying instrument increases. Long positions will profit if the value of
the instrument increases. Simultaneously engaging in long investing and short
selling reduces the net exposure of the overall portfolio to general market
movements. Relative value positions may be taken as well in the various
strategies. Relative value strategies capitalize on price differences between
similar securities or relative value among securities of the same company.
  
The Fund may use all or some of the following strategies to varying degrees,
depending on market conditions, and may add additional strategies. Principal
may allocate 0 to 100% of the Fund's assets to any of these strategies at any
time.
  
Credit Long/Short and Distressed Credit. This strategy utilizes a flexible
investment approach that allocates investments across a global range of
investment opportunities related to credit, currencies and interest rates, while
employing risk management strategies. This strategy invests in fixed income
securities and instruments and may invest in both investment-grade securities
and high yield, below-investment grade securities (sometimes called "junk bonds"
and are rated at the time of purchase BB+ or lower by S&P or rated Ba1 or lower
by Moody's or of equivalent rating as determined by the sub-advisor). This
strategy may also invest in the following securities: securities denominated in
foreign currencies and in U.S. dollar denominated securities of foreign issuers,
preferred securities, convertible securities, Rule 144A securities, mortgage or
asset-backed securities, floating rate debt (including bank loans), distressed
investments, emerging markets, equities and derivative instruments, such as
options, futures contracts, forwards or swap agreements. This strategy may
utilize derivative instruments in an effort to minimize volatility. Also, at
times, this strategy expects to gain its investment exposure substantially
through the use of derivatives. The notional value of this strategy's long and
short investment exposures may at times each reach 100% of the assets invested
in this strategy (excluding instruments used primarily for duration, yield
curve, and interest rate management and short-term investments), although these
exposures may be higher or lower at any given time. This strategy may purchase
or sell securities on a when-issued, delayed delivery or forward commitment
basis and may engage in short sales. The strategy may, without limitation, seek
to obtain market exposure to the securities in which it primarily invests by
entering into a series of purchase and sale contracts or by using other
investment techniques (such as buy backs or dollar rolls).
  
Equity Long/Short. This strategy provides long and short exposure to a
diversified portfolio of equities which involves simultaneously investing in
equities (i.e., investing long) the sub-advisor expects to increase in value
(securities the sub-advisor believes are undervalued) and either selling
equities (i.e., short sales or short selling) the sub-advisor expects to
decrease in value (securities the sub-advisor believes are overvalued) or
hedging the equity exposure in another way. Long/short equity may maintain
overweights of industry exposures and also seeks to exploit pricing
inefficiencies between related equity securities. This strategy has available
two methods of analysis: fundamental analysis, a method of security analysis
that involves examining a company's financial statements and operations,
especially sales, earnings, products, management and competition and
quantitative analysis, a method of security analysis that involves use of
mathematical models to examine a company's measurable characteristics such
as revenue, earnings, margins and market share.

Equity Market Neutral. This strategy seeks to profit by exploiting pricing
inefficiencies between related equity securities and neutralizing exposure
to market risk by maintaining long and short positions. Equity market neutral
is not expected to have industry overweights.
  
Dedicated Short Bias. The dedicated short bias strategy seeks to profit by
shorting stocks that have negative market sentiment and neutralizing exposure to
market risk by maintaining long and short positions.
  
Global Macro. Global macro strategies seek to profit from movement in the prices
of securities that are highly sensitive to macroeconomic conditions, across a
broad spectrum of assets. This strategy provides long and short exposure to
developed country equities, currencies, and bonds markets.

Emerging Markets. This strategy seeks to profit from investing in equities,
bonds, and currencies of issuers in emerging markets. This strategy provides
long and short exposure to emerging country equity, debt, and currency markets,
and long and short exposure to a basket of liquid equity securities traded on
emerging and developed market exchanges.
  
Convertible Arbitrage. Convertible arbitrage strategies seek to profit from the
complexity of the pricing of convertible bonds (which contain elements of both a
fixed income security and an equity option) by structuring trades using multiple
securities within the capital structure of a convertible bond issuer. The Fund
may purchase the convertible bond of a given issuer and simultaneously sell
short the common stock of that same issuer to take advantage of a mispricing of
either security. This strategy takes positions in various global convertible
debt and preferred securities and an offsetting position in various global
equities directly linked to the convertible securities. In implementing this
strategy, the Fund may use derivatives to hedge against a decline in interest
rates or credit exposure.
  
Managed Futures. Managed futures strategies seek to profit from the design and
implementation of quantitative selection models to help predict upcoming
movements in any combination of fixed income, currency, or equity markets. This
strategy provides long and short exposure to developed country equities, bonds
and currency markets and long and short exposure to emerging country equity and
currency markets.
  
Event Driven. Event driven strategies seek to profit from investing in the
securities of companies based not on a value or growth investment style but
rather on the basis that a specific event or catalyst will affect future prices.
This strategy attempts to capitalize on price discrepancies and returns
generated by corporate activity, such as merger arbitrage. In merger arbitrage,
the Fund will employ a diversified, disciplined strategy to attempt to capture
the returns from holding a long/short portfolio of stocks of companies involved
in mergers.
  
Fixed Income Arbitrage. Fixed income arbitrage seeks to profit from exploiting
mispricing of various, liquid fixed income or interest rate sensitive
securities. This strategy provides long and short exposure to developed country
bond and currency markets, long and short exposure to investment grade credit
markets and long and short exposure to forward mortgage-backed securities
trading in the to be announced ("TBA") market.

Principal Risks

The Fund may be an appropriate investment for investors who seek long-term
capital appreciation and who can accept the risks of investing in a variety of
global markets and a variety of instruments.

The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:
   
Active Trading Risk. Actively trading portfolio securities may accelerate
realization of taxable gains and losses, lower fund performance and may result
in high portfolio turnover rates and increased brokerage costs.
  
Arbitrage Trading Risk. The underlying relationships between securities in which
the fund takes arbitrage investment positions may change in an adverse manner,
in which case the fund may realize losses.
  
Asset Allocation Risk. A fund's selection and weighting of asset classes may
cause it to underperform other funds with a similar investment objective.
  
Bank Loans Risk. Changes in economic conditions are likely to cause issuers of
bank loans (also known as senior floating rate interests) to be unable to meet
their obligations. In addition, the value of the collateral securing the loan
may decline, causing a loan to be substantially unsecured. Underlying credit
agreements governing the bank loans, reliance on market makers, priority of
repayment and overall market volatility may harm the liquidity of loans.
  
Basis Risk. A hedge using derivatives and/or securities could expose the fund to
basis risk. Basis risk could arise when the change in price of the hedge may not
match the change in price of the asset it hedges. In other words, the hedge
moves in a direction that does not match the asset it is trying to hedge.
  
Counterparty Risk. Counterparty risk is the risk that the counterparty to a
derivatives contract or repurchase agreement, the borrower of a portfolio's
securities, or other obligation, will be unable or unwilling to make timely
principal, interest, or settlement payments, or otherwise to honor its
obligations.
  
Convertible Securities Risk. Convertible securities can be bonds, notes,
debentures, preferred stock or other securities which are convertible into
common stock. Convertible securities are subject to both the credit and interest
rate risks associated with fixed income securities and to the stock market risk
associated with equity securities.
  
Derivatives Risk. Transactions in derivatives (such as options, futures, currency
contracts, and swaps) may increase volatility, cause the liquidation of portfolio
positions when not advantageous to do so and produce disproportionate losses.
  
Distressed Investments Risk. A fund's investment in instruments involving loans,
loan participations, bonds, notes, non-performing and sub-performing mortgage
loans, many of which are not publicly traded, may involve a substantial degree
of risk for the following reasons. These instruments may become illiquid and the
prices of such instruments may be extremely volatile. Valuing such instruments
may be difficult and a fund may lose all of its investment, or it may be
required to accept cash or securities with a value less than the fund's original
investment. Issuers of distressed securities are typically in a weak financial
condition and may default, in which case the fund may lose its entire
investment.
  
Emerging Market Risk. Investments in emerging market countries may have more
risk than those in developed market countries because the emerging markets are
less developed and more illiquid. Emerging market countries can also be subject
to increased social, economic, regulatory, and political uncertainties and can
be extremely volatile.
  
Equity Securities Risk. Equity securities (common, convertible preferred stocks
and other securities whose values are tied to the price of stocks, such as
rights, warrants and convertible debt securities) could decline in value if the
issuer's financial condition declines or in response to overall market and
economic conditions. A fund's principal market segment(s), such as large cap,
mid cap or small cap stocks, or growth or value stocks, may underperform other
market segments or the equity markets as a whole. Investments in smaller
companies and mid-size companies may involve greater risk and price volatility
than investments in larger, more mature companies.
  
Event-Driven Trading Risk. Event-driven trading involves the risk that the
special situation may not occur as anticipated, if at all, and that the market
price of a stock declines.
  
Fixed-Income Securities Risk. Fixed-income securities are subject to interest
rate risk and credit quality risk. The market value of fixed-income securities
generally declines when interest rates rise, and an issuer of fixed-income
securities could default on its payment obligations.
  
Foreign Securities Risk. The risks of foreign securities include loss of value
as a result of: political or economic instability; nationalization, expropriation
or confiscatory taxation; changes in foreign exchange rates and foreign exchange
restrictions; settlement delays; and limited government regulation (including
less stringent reporting, accounting, and disclosure standards than are required
of U.S. companies).
  
High Yield Securities Risk. High yield fixed-income securities (commonly
referred to as "junk bonds") are subject to greater credit quality risk than
higher rated fixed-income securities and should be considered speculative.

Leverage Risk. Leverage created by borrowing or certain types of transactions or
investments, such as reverse repurchase agreements, loans of portfolio securities,
and the use of when-issued, delayed delivery or forward commitment transactions,
or derivative instruments, may impair the fund's liquidity, cause it to liquidate
positions at an unfavorable time, increase volatility of the fund's net asset value,
or diminish the fund's performance.
  
Non-Diversification Risk. A non-diversified fund may invest a high percentage
of its assets in the securities of a small number of issuers and is more likely
than diversified funds to be significantly affected by a specific security's
poor performance.
  
Portfolio Duration Risk. Portfolio duration is a measure of the expected life
of a fixed-income security and its sensitivity to changes in interest rates. The
longer a fund's average portfolio duration, the more sensitive the fund will be
to changes in interest rates.
  
Preferred Securities Risk. Preferred securities are junior subordinated
securities in a company's capital structure and therefore can be subject to
greater credit and liquidation risk. An issuer of preferred securities could
redeem the security prior to the stated maturity date and reduce the return of
the security.
  
Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed
securities may have to be reinvested at lower rates. A reduction in prepayments
may increase the effective maturities of these securities, exposing them to the
risk of decline in market value over time (extension risk).
  
Risk of Being an Underlying Fund. An underlying fund of a fund of funds may
experience relatively large redemptions or investments as the fund of funds
periodically reallocates or rebalances its assets. These transactions may cause
the underlying fund to sell portfolio securities to meet such redemptions, or to
invest cash from such investments, at times it would not otherwise do so, and
may as a result increase transaction costs and adversely affect underlying fund
performance.
  
Short Sale Risk. A short sale involves the sale by the fund of a security that
it does not own with the hope of purchasing the same security at a later date at
a lower price. A fund may also enter into a short derivative position through a
futures contract or swap agreement. If the price of the security or derivative
has increased during this time, then the fund will incur a loss equal to the
increase in price from the time that the short sale was entered into plus any
premiums and interest paid to the third party. Therefore, short sales involve
the risk that losses may be exaggerated, potentially losing more money than the
actual cost of the investment. Also, there is the risk that the third party to
the short sale may fail to honor its contract terms, causing a loss to the fund.
  
Value Stock Risk. The market may not recognize the intrinsic value of value
stocks for a long time, or they may be appropriately priced at the time of
purchase.

Performance

No performance information is shown because the Fund has not yet had a calendar
year of performance. The Fund's performance will be benchmarked against the HRFI
(Hedge Fund Research Inc.) Funds-of-Funds Composite Index.

[1] Other Expenses are estimated for the year ending August 31, 2012

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense and dividend and interest expense on short sales, through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.75% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Preferred Securities Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide current income.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	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	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 most recent fiscal year, the Fund's annualized portfolio turnover rate was 16.8% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	16.80%
Expenses, Restated to Reflect Current	rr_ExpensesRestatedToReflectCurrent	Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in preferred securities at the time of purchase. Preferred securities generally pay fixed rate dividends (though some are adjustable rate) and typically have "preference" over common stock in the payment of dividends and the liquidation of a company's assets, but are junior to all forms of the company's debt. Most of the securities purchased by the Fund are preferred securities of companies rated at the time of purchase BBB- or higher by Standard & Poor's Rating Service ("S&P") or Baa3 or higher by Moody's Investor Service, Inc. ("Moody's") or, if unrated, of comparable quality in the opinion of the Sub-Advisor. The Fund also invests up to 15% of its assets in high yield, below investment grade quality debt (sometimes called "junk bonds" and rated at the time of purchase BB+ or lower by S&P or rated Ba1 or lower by Moody's or of equivalent quality as determined by the Sub-Advisor).    The Fund will concentrate its investments (invest more than 25% of its net assets) in securities in the U.S. and non-U.S financial services (i.e., banking, insurance and commercial finance,) industry. The Fund also regularly invests in the real estate investment trust (i.e. REIT) and utility industries.
Investment Strategy, Portfolio Concentration	rr_StrategyPortfolioConcentration	The Fund will concentrate its investments (invest more than 25% of its net assets) in securities in the U.S. and non-U.S financial services (i.e., banking, insurance and commercial finance,) industry. The Fund also regularly invests in the real estate investment trust (i.e. REIT) and utility industries.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	Principal Risks The Fund may be an appropriate investment for investors who are seeking dividends to generate income or to reinvest for growth and are willing to accept fluctuations in the value of the investment.    The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:    Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies.    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations. Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; changes in foreign exchange rates and foreign exchange restrictions; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies).    High Yield Securities Risk. High yield fixed-income securities (commonly referred to as "junk bonds") are subject to greater credit quality risk than higher rated fixed-income securities and should be considered speculative.    Industry Concentration Risk. A fund that concentrates investments in a particular industry or group of industries (e.g., energy, real estate, technology, financial services) has greater exposure than other funds to market, economic and other factors affecting that industry.    Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates.    Preferred Securities Risk. Preferred securities are junior subordinated securities in a company's capital structure and therefore can be subject to greater credit and liquidation risk. An issuer of preferred securities could redeem the security prior to the stated maturity date and reduce the return of the security.    Real Estate Investment Trusts ("REITs") Risk. A REIT could fail to qualify for tax-free pass-through of income under the Internal Revenue Code, and fund shareholders will indirectly bear their proportionate share of the expenses of REITs in which the fund invests.    Real Estate Securities Risk. Real estate securities are subject to the risks associated with direct ownership of real estate, including declines in value, adverse economic conditions, increases in expenses, regulatory changes and environmental problems. Risk of Being an Underlying Fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The following information provides an indication of the risks of investing in the Fund. The bar chart shows the investment returns of the Fund's Class J shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund). These annual returns do not reflect sales charges; if they did, returns would be lower. The table shows, for Class J shares of the Fund and for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund's average annual total returns compare to the returns of one or more broad-based market indices. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You may get updated performance information online at www.principalfunds.com or by calling 1-800-222-5852.    Class J shares were first sold on December 29, 2003. The returns for the periods prior to that date are based on the performance of the Institutional Class shares adjusted to reflect the fees and expenses of Class J shares. The adjustments result in performance for such periods that is no higher than the historical performance of the Institutional Class shares. The Institutional Class shares were first sold on May 1, 2002.    Performance of a blended index shows how the Fund's performance compares to an index with similar investment objectives. Performance of the components of the blended index are also shown. The weightings for the Preferreds Blended Index in the Average Annual Total Returns table are 50% BofA Merrill Lynch Fixed Rate Preferred Securities and 50% Barclays Capital U.S. Tier I Capital Securities Index. The custom or blended index returns reflect the allocation in effect for the time period(s) for which fund returns are disclosed. Previous weightings or allocations of the custom or blended index are not restated.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides an indication of the risks of investing in the Fund.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-222-5852
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.principalfunds.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Total Returns as of December 31 each year (Class J shares)	[1]
Bar Chart, Does Not Reflect Sales Loads	rr_BarChartDoesNotReflectSalesLoads	These annual returns do not reflect sales charges; if they did, returns would be lower.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Highest return for a quarter during the period of the bar     Q2 '09      38.56% chart above:                                                            Lowest return for a quarter during the period of the bar      Q3 '08     -21.11% chart above:
Index No Deduction for Fees, Expenses, Taxes	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction 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 and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an 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(k) plans or individual retirement accounts.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an 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(k) plans or individual retirement accounts.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns For the periods ended December 31, 2011
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | BofA Merrill Lynch Fixed Rate Preferred Securities Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	BofA Merrill Lynch Fixed Rate Preferred Securities Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	4.11%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.19%)
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.42%
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Barclays Capital U.S. Tier I Capital Securities Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Barclays Capital U.S. Tier I Capital Securities Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(0.53%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.71%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	4.87%
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Preferreds Blended Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Preferreds Blended Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.81%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	0.01%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	3.38%
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Class J
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.71%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.45%
Other Expenses	rr_OtherExpensesOverAssets	0.34%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.50%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.20%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.30%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2012-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	232
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	454
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	800
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,773
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	132
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	454
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	800
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,773
Annual Return 2003	rr_AnnualReturn2003	9.70%
Annual Return 2004	rr_AnnualReturn2004	3.57%
Annual Return 2005	rr_AnnualReturn2005	0.69%
Annual Return 2006	rr_AnnualReturn2006	6.11%
Annual Return 2007	rr_AnnualReturn2007	(8.69%)
Annual Return 2008	rr_AnnualReturn2008	(22.86%)
Annual Return 2009	rr_AnnualReturn2009	45.38%
Annual Return 2010	rr_AnnualReturn2010	15.81%
Annual Return 2011	rr_AnnualReturn2011	0.99%
Year to Date Return, Label	rr_YearToDateReturnLabel	The year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	7.79%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest return for a quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	38.56%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest return for a quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.11%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return Before Taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.04%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	3.67%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	4.41%
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Class J | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return After Taxes on Distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(1.80%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.66%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.68%
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Class J | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return After Taxes on Distribution and Sale of Fund Shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.35%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	2.00%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.80%

[1] The year-to-date return as of March 31, 2012 was 7.79% for Class J shares.

[2] Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.

[3] Effective January 1, 2012, Principal Funds Distributor, Inc. ("the Distributor") has contractually agreed to limit the Distribution Fees attributable to Class J through December 31, 2012. The limit will maintain the level of Distribution Fees not to exceed 0.25%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and the Distributor, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

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Blue Chip Fund (Prospectus Summary) | Blue Chip Fund

Blue Chip Fund

Objective:

The Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

Shareholder Fees (fees paid directly from your investment): None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Blue Chip Fund Institutional Class
Management Fees		0.70%
Other Expenses	[1]	0.51%
Total Annual Fund Operating Expenses		1.21%
Expense Reimbursement	[2]	0.46%
Total Annual Fund Expenses After Expense Reimbursement		0.75%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Blue Chip Fund Institutional Class	77	339

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.
This is a new Fund and does not yet have a portfolio turnover rate to disclose.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets, plus
borrowings for investment purposes, in equity securities of companies with large
market capitalizations (those with market capitalizations similar to companies in
the Russell 1000 Growth® Index (as of December 31, 2011, this range was between
approximately $578 million and $401.25 billion) at the time of purchase. The
Fund may invest in foreign securities.
  
The Fund invests in growth equity securities; growth orientation emphasizes
buying equity securities of companies whose potential for growth of capital
and earnings is expected to be above average.

Principal Risks

The Fund may be an appropriate investment for investors seeking long-term growth
of capital and willing to accept the potential for short-term fluctuations in
the value of investments.

The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:

Equity Securities Risk. Equity securities (common, convertible preferred stocks
and other securities whose values are tied to the price of stocks, such as
rights, warrants and convertible debt securities) could decline in value if the
issuer's financial condition declines or in response to overall market and
economic conditions. A fund's principal market segment(s), such as large cap,
mid cap or small cap stocks, or growth or value stocks, may underperform other
market segments or the equity markets as a whole. Investments in smaller
companies and mid-size companies may involve greater risk and price volatility
than investments in larger, more mature companies.

Foreign Securities Risk. The risks of foreign securities include loss of value
as a result of: political or economic instability; nationalization, expropriation
or confiscatory taxation; changes in foreign exchange rates and foreign exchange
restrictions; settlement delays; and limited government regulation (including
less stringent reporting, accounting, and disclosure standards than are required
of U.S. companies).
  
Growth Stock Risk. If growth companies do not increase their earnings at a rate
expected by investors, the market price of the stock may decline significantly,
even if earnings show an absolute increase. Growth company stocks also typically
lack the dividend yield that can lessen price declines in market downturns.

Performance

No performance information is shown because the Fund has not yet had a calendar
year of performance. The Fund's performance will be benchmarked against the
Russell 1000 Growth Index.

[1] Other Expenses are estimated for the year ending August 31, 2012.

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Institutional class shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 0.75%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

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Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Global Multi-Strategy Fund (Prospectus Summary) | Global Multi-Strategy Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Global Multi-Strategy Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund seeks to achieve long-term capital appreciation with an emphasis on positive total returns and relatively low volatility.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Information about discounts is available from your financial professional and in "Choosing a Share Class and The Costs of Investing" beginning on page 38 of the Fund's prospectus and "Multiple Class Structure" beginning on page 59 of the Fund's Statement of Additional Information.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	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	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. This is a new Fund and does not yet have a portfolio turnover rate to disclose.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated for the year ending August 31, 2012
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Principal Management Corporation ("Principal"), the Fund's investment adviser, allocates the Fund's assets among one or more of the investment strategies described below, which are executed by one or more of the Fund's sub-advisors. In making these allocations, Principal seeks to combine the strategies of the sub-advisors efficiently and systematically so that the Fund generates, through a diversified set of investment strategies, a positive total return with relatively low volatility and low sensitivity or correlation to market indices. By allocating the Fund's assets among a variety of investment strategies, which will vary from time-to-time, the Fund seeks to lessen risk and reduce volatility. Principal may also direct a sub-advisor to reduce or omit its investment in certain assets or asset classes in an effort to achieve its desired combination of the Fund's strategies. In pursuing its strategies, the Fund invests in a broad range of instruments including, but not limited to, equities, bonds, currencies, convertible securities and derivatives such as futures, options, swaps (including, for example, credit default, interest rate, and currency swaps) and forwards. The Fund intends to engage in many derivative transactions to gain exposure to a variety of securities or attempt to reduce risk. The Fund intends to invest in securities that are tied economically to a number of countries throughout the world, including the U.S.; however, the Fund has no requirements as to the amount of its net assets that it invests in foreign securities. The Fund is considered non-diversified, which means it can invest a higher percentage of assets in securities of individual issuers than a diversified fund. The Fund may actively trade securities.    Some of the strategies take long and/or short positions. When taking a short position, the Fund may sell an instrument that it does not own and then borrow to meet its settlement obligations. The Fund may take short positions in futures, forwards or swaps. A short position will benefit from a decrease in price of the underlying instrument and will lose value if the price of the underlying instrument increases. Long positions will profit if the value of the instrument increases. Simultaneously engaging in long investing and short selling reduces the net exposure of the overall portfolio to general market movements. Relative value positions may be taken as well in the various strategies. Relative value strategies capitalize on price differences between similar securities or relative value among securities of the same company.    The Fund may use all or some of the following strategies to varying degrees, depending on market conditions, and may add additional strategies. Principal may allocate 0 to 100% of the Fund's assets to any of these strategies at any time.    Credit Long/Short and Distressed Credit. This strategy utilizes a flexible investment approach that allocates investments across a global range of investment opportunities related to credit, currencies and interest rates, while employing risk management strategies. This strategy invests in fixed income securities and instruments and may invest in both investment-grade securities and high yield, below-investment grade securities (sometimes called "junk bonds" and are rated at the time of purchase BB+ or lower by S&P or rated Ba1 or lower by Moody's or of equivalent rating as determined by the sub-advisor). This strategy may also invest in the following securities: securities denominated in foreign currencies and in U.S. dollar denominated securities of foreign issuers, preferred securities, convertible securities, Rule 144A securities, mortgage or asset-backed securities, floating rate debt (including bank loans), distressed investments, emerging markets, equities and derivative instruments, such as options, futures contracts, forwards or swap agreements. This strategy may utilize derivative instruments in an effort to minimize volatility. Also, at times, this strategy expects to gain its investment exposure substantially through the use of derivatives. The notional value of this strategy's long and short investment exposures may at times each reach 100% of the assets invested in this strategy (excluding instruments used primarily for duration, yield curve, and interest rate management and short-term investments), although these exposures may be higher or lower at any given time. This strategy may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short sales. The strategy may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as buy backs or dollar rolls).    Equity Long/Short. This strategy provides long and short exposure to a diversified portfolio of equities which involves simultaneously investing in equities (i.e., investing long) the sub-advisor expects to increase in value (securities the sub-advisor believes are undervalued) and either selling equities (i.e., short sales or short selling) the sub-advisor expects to decrease in value (securities the sub-advisor believes are overvalued) or hedging the equity exposure in another way. Long/short equity may maintain overweights of industry exposures and also seeks to exploit pricing inefficiencies between related equity securities. This strategy has available two methods of analysis: fundamental analysis, a method of security analysis that involves examining a company's financial statements and operations, especially sales, earnings, products, management and competition and quantitative analysis, a method of security analysis that involves use of mathematical models to examine a company's measurable characteristics such as revenue, earnings, margins and market share. Equity Market Neutral. This strategy seeks to profit by exploiting pricing inefficiencies between related equity securities and neutralizing exposure to market risk by maintaining long and short positions. Equity market neutral is not expected to have industry overweights.    Dedicated Short Bias. The dedicated short bias strategy seeks to profit by shorting stocks that have negative market sentiment and neutralizing exposure to market risk by maintaining long and short positions.    Global Macro. Global macro strategies seek to profit from movement in the prices of securities that are highly sensitive to macroeconomic conditions, across a broad spectrum of assets. This strategy provides long and short exposure to developed country equities, currencies, and bonds markets. Emerging Markets. This strategy seeks to profit from investing in equities, bonds, and currencies of issuers in emerging markets. This strategy provides long and short exposure to emerging country equity, debt, and currency markets, and long and short exposure to a basket of liquid equity securities traded on emerging and developed market exchanges.    Convertible Arbitrage. Convertible arbitrage strategies seek to profit from the complexity of the pricing of convertible bonds (which contain elements of both a fixed income security and an equity option) by structuring trades using multiple securities within the capital structure of a convertible bond issuer. The Fund may purchase the convertible bond of a given issuer and simultaneously sell short the common stock of that same issuer to take advantage of a mispricing of either security. This strategy takes positions in various global convertible debt and preferred securities and an offsetting position in various global equities directly linked to the convertible securities. In implementing this strategy, the Fund may use derivatives to hedge against a decline in interest rates or credit exposure.    Managed Futures. Managed futures strategies seek to profit from the design and implementation of quantitative selection models to help predict upcoming movements in any combination of fixed income, currency, or equity markets. This strategy provides long and short exposure to developed country equities, bonds and currency markets and long and short exposure to emerging country equity and currency markets.    Event Driven. Event driven strategies seek to profit from investing in the securities of companies based not on a value or growth investment style but rather on the basis that a specific event or catalyst will affect future prices. This strategy attempts to capitalize on price discrepancies and returns generated by corporate activity, such as merger arbitrage. In merger arbitrage, the Fund will employ a diversified, disciplined strategy to attempt to capture the returns from holding a long/short portfolio of stocks of companies involved in mergers.    Fixed Income Arbitrage. Fixed income arbitrage seeks to profit from exploiting mispricing of various, liquid fixed income or interest rate sensitive securities. This strategy provides long and short exposure to developed country bond and currency markets, long and short exposure to investment grade credit markets and long and short exposure to forward mortgage-backed securities trading in the to be announced ("TBA") market.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors who seek long-term capital appreciation and who can accept the risks of investing in a variety of global markets and a variety of instruments. The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:     Active Trading Risk. Actively trading portfolio securities may accelerate realization of taxable gains and losses, lower fund performance and may result in high portfolio turnover rates and increased brokerage costs.    Arbitrage Trading Risk. The underlying relationships between securities in which the fund takes arbitrage investment positions may change in an adverse manner, in which case the fund may realize losses.    Asset Allocation Risk. A fund's selection and weighting of asset classes may cause it to underperform other funds with a similar investment objective.    Bank Loans Risk. Changes in economic conditions are likely to cause issuers of bank loans (also known as senior floating rate interests) to be unable to meet their obligations. In addition, the value of the collateral securing the loan may decline, causing a loan to be substantially unsecured. Underlying credit agreements governing the bank loans, reliance on market makers, priority of repayment and overall market volatility may harm the liquidity of loans.    Basis Risk. A hedge using derivatives and/or securities could expose the fund to basis risk. Basis risk could arise when the change in price of the hedge may not match the change in price of the asset it hedges. In other words, the hedge moves in a direction that does not match the asset it is trying to hedge.    Counterparty Risk. Counterparty risk is the risk that the counterparty to a derivatives contract or repurchase agreement, the borrower of a portfolio's securities, or other obligation, will be unable or unwilling to make timely principal, interest, or settlement payments, or otherwise to honor its obligations.    Convertible Securities Risk. Convertible securities can be bonds, notes, debentures, preferred stock or other securities which are convertible into common stock. Convertible securities are subject to both the credit and interest rate risks associated with fixed income securities and to the stock market risk associated with equity securities.    Derivatives Risk. Transactions in derivatives (such as options, futures, currency contracts, and swaps) may increase volatility, cause the liquidation of portfolio positions when not advantageous to do so and produce disproportionate losses.    Distressed Investments Risk. A fund's investment in instruments involving loans, loan participations, bonds, notes, non-performing and sub-performing mortgage loans, many of which are not publicly traded, may involve a substantial degree of risk for the following reasons. These instruments may become illiquid and the prices of such instruments may be extremely volatile. Valuing such instruments may be difficult and a fund may lose all of its investment, or it may be required to accept cash or securities with a value less than the fund's original investment. Issuers of distressed securities are typically in a weak financial condition and may default, in which case the fund may lose its entire investment.    Emerging Market Risk. Investments in emerging market countries may have more risk than those in developed market countries because the emerging markets are less developed and more illiquid. Emerging market countries can also be subject to increased social, economic, regulatory, and political uncertainties and can be extremely volatile.    Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies.    Event-Driven Trading Risk. Event-driven trading involves the risk that the special situation may not occur as anticipated, if at all, and that the market price of a stock declines.    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations.    Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; changes in foreign exchange rates and foreign exchange restrictions; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies).    High Yield Securities Risk. High yield fixed-income securities (commonly referred to as "junk bonds") are subject to greater credit quality risk than higher rated fixed-income securities and should be considered speculative. Leverage Risk. Leverage created by borrowing or certain types of transactions or investments, such as reverse repurchase agreements, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions, or derivative instruments, may impair the fund's liquidity, cause it to liquidate positions at an unfavorable time, increase volatility of the fund's net asset value, or diminish the fund's performance.    Non-Diversification Risk. A non-diversified fund may invest a high percentage of its assets in the securities of a small number of issuers and is more likely than diversified funds to be significantly affected by a specific security's poor performance.    Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates.    Preferred Securities Risk. Preferred securities are junior subordinated securities in a company's capital structure and therefore can be subject to greater credit and liquidation risk. An issuer of preferred securities could redeem the security prior to the stated maturity date and reduce the return of the security.    Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed securities may have to be reinvested at lower rates. A reduction in prepayments may increase the effective maturities of these securities, exposing them to the risk of decline in market value over time (extension risk).    Risk of Being an Underlying Fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance.    Short Sale Risk. A short sale involves the sale by the fund of a security that it does not own with the hope of purchasing the same security at a later date at a lower price. A fund may also enter into a short derivative position through a futures contract or swap agreement. If the price of the security or derivative has increased during this time, then the fund will incur a loss equal to the increase in price from the time that the short sale was entered into plus any premiums and interest paid to the third party. Therefore, short sales involve the risk that losses may be exaggerated, potentially losing more money than the actual cost of the investment. Also, there is the risk that the third party to the short sale may fail to honor its contract terms, causing a loss to the fund.    Value Stock Risk. The market may not recognize the intrinsic value of value stocks for a long time, or they may be appropriately priced at the time of purchase.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	A non-diversified fund may invest a high percentage of its assets in the securities of a small number of issuers and is more likely than diversified funds to be significantly affected by a specific security's poor performance.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance information is shown because the Fund has not yet had a calendar year of performance. The Fund's performance will be benchmarked against the HRFI (Hedge Fund Research Inc.) Funds-of-Funds Composite Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance information is shown because the Fund has not yet had a calendar year of performance.
Global Multi-Strategy Fund (Prospectus Summary) | Global Multi-Strategy Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	1.60%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Dividend and Interest Expense on Short Sales	rr_Component1OtherExpensesOverAssets	1.56%	[1]
Remainder of Other Expenses	rr_Component2OtherExpensesOverAssets	0.45%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	4.61%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.30%)	[2]
Total Annual Fund Operating Expenses after Expense Reimbursement	rr_NetExpensesOverAssets	4.31%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	532
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	1,364
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	432
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	1,364

[1] Other Expenses are estimated for the year ending August 31, 2012

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense and dividend and interest expense on short sales, through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.75% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Aug. 31, 2011
Registrant Name	dei_EntityRegistrantName	PRINCIPAL FUNDS INC
Central Index Key	dei_EntityCentralIndexKey	0000898745
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 13, 2012
Document Effective Date	dei_DocumentEffectiveDate	Jun. 13, 2012
Global Multi-Strategy Fund (Prospectus Summary) | Global Multi-Strategy Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PMSCX
Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PMOAX
Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PMODX
Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PMDDX
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund | Class J Shares
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PBIJX
Preferred Securities Fund (Prospectus Summary) | Preferred Securities Fund | Class J
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PPSJX
Blue Chip Fund (Prospectus Summary) | Blue Chip Fund | Institutional Class
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PBCKX

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Small-MidCap Dividend Income Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund primarily seeks to provide a relatively high level of current income and long-term growth of income
Investment Objective, Secondary	rr_ObjectiveSecondaryTextBlock	and secondarily long-term growth of capital, while investing primarily in small- to mid-capitalization companies.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Information about discounts is available from your financial professional and in "Choosing a Share Class and The Costs of Investing" beginning on page 38 of the Fund's prospectus and "Multiple Class Structure" beginning on page 59 of the Fund's Statement of Additional Information.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	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	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. From June 6, 2011, date operations commenced, through August 31, 2011, the Fund's annualized portfolio turnover rate was 43.5% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	43.50%
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses estimated for the year ending August 31, 2012.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in dividend-paying equity securities of companies with small to medium market capitalizations (those with market capitalizations ranging from between $200 million and $7 billion) at the time of purchase. The Fund invests in value equity securities, an investment strategy that emphasizes buying equity securities that appear to be undervalued. The Fund will invest in the securities of foreign issuers, real estate investment trusts, preferred securities, convertible securities, fixed-income securities, master limited partnerships, and royalty trusts.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors who seek dividends to generate income or to reinvest for growth and who can accept fluctuations in the value of investments and the risks of investing in real estate investment trust securities and foreign securities.    The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:    Convertible Securities Risk. Convertible securities can be bonds, notes, debentures, preferred stock or other securities which are convertible into common stock. Convertible securities are subject to both the credit and interest rate risks associated with fixed income securities and to the stock market risk associated with equity securities.    Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies.    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations.    Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; changes in foreign exchange rates and foreign exchange restrictions; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies).    Master Limited Partnership ("MLP") Risk. MLPs are publicly-traded limited partnership interests or units. An MLP that invests in a particular industry (e.g., oil and gas) will be harmed by detrimental economic events within that industry. As partnerships, MLPs may be subject to less regulation (and less protection for investors) under state laws than corporations. In addition, MLPs may be subject to state taxation in certain jurisdictions, which may reduce the amount of income an MLP pays to its investors.    Preferred Securities Risk. Preferred securities are junior subordinated securities in a company's capital structure and therefore can be subject to greater credit and liquidation risk. An issuer of preferred securities could redeem the security prior to the stated maturity date and reduce the return of the security.    Real Estate Investment Trusts ("REITs") Risk. A REIT could fail to qualify for tax-free pass-through of income under the Internal Revenue Code, and fund shareholders will indirectly bear their proportionate share of the expenses of REITs in which the fund invests.    Real Estate Securities Risk. Real estate securities are subject to the risks associated with direct ownership of real estate, including declines in value, adverse economic conditions, increases in expenses, regulatory changes and environmental problems. Risk of Being an Underlying Fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance.    Royalty Trust Risk. A royalty trust generally acquires an interest in natural resource or chemical companies and distributes the income it receives to its investors. A sustained decline in demand for natural resource and related products could adversely affect royalty trust revenues and cash flows. Such a decline could result from a recession or other adverse economic conditions, an increase in the market price of the underlying commodity, higher taxes or other regulatory actions that increase costs, or a shift in consumer demand. Rising interest rates could adversely affect the performance, and limit the capital appreciation, of royalty trusts because of the increased availability of alternative investments at more competitive yields. Fund shareholders will indirectly bear their proportionate share of the royalty trusts' expenses.    Value Stock Risk. The market may not recognize the intrinsic value of value stocks for a long time, or they may be appropriately priced at the time of purchase.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance information is shown because the Fund has not yet had a calendar year of performance. The Fund's performance will be benchmarked against the Russell 2500 Value Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance information is shown because the Fund has not yet had a calendar year of performance.
Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.39%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.19%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total Annual Fund Operating Expenses after Expense Reimbursement	rr_NetExpensesOverAssets	2.15%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	318
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	681
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	218
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	681

[1] Other Expenses estimated for the year ending August 31, 2012.

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.15% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Opportunistic Municipal Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide a high level of income that is exempt from federal income tax while protecting investors' capital.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in Principal Funds, Inc. More information about these and other discounts is available from your financial professional and in "Choosing a Share Class and The Costs of Investing" beginning on page 38 of the Fund's prospectus and "Multiple Class Structure" beginning on page 59 of the Fund's Statement of Additional Information.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	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	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. This is a new Fund and does not yet have a portfolio turnover rate to disclose.
Expense Breakpoint, Discounts	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in Principal Funds, Inc.
Expense Breakpoint, Minimum Investment Required Amount	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	100,000
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated for the year ending August 31, 2012.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in municipal obligations (securities issued by or on behalf of state or local governments and other public authorities). Municipal obligations pay interest that is exempt from federal income tax. The Fund has a flexible investment strategy and may invest in obligations of any duration and credit quality, including below investment grade bonds (rated at the time of purchase Ba1 or lower by Moody's or BB+ or lower by S&P, sometimes called "junk bonds") as rated by at least one independent rating agency, or if unrated, judged to be of comparable quality by the Fund's Sub-Advisor. The Fund may invest in other debt obligations, including (but not limited to) taxable municipal obligations, U.S. Treasury securities, obligations of the U.S. Government, its agencies and instrumentalities ("Agency Securities") and inverse floating rate obligations, which are generally more volatile than other types of municipal obligations. The Fund may invest in exchange-traded funds (ETFs) to gain exposure to the municipal market. The Fund may purchase derivative instruments, which derive their value from another instrument, security or index. The Fund may purchase or sell various kinds of financial futures contracts to hedge against changes in interest rates or as a substitute for the purchase of portfolio securities. The Fund also may enter into interest rate swaps and credit derivatives, which may include credit default swaps.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors who are seeking monthly, federally tax-exempt dividends to produce income or to reinvest for modest growth and are willing to accept fluctuations in the value of their investment. The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:    Counterparty Risk. Counterparty risk is the risk that the counterparty to a derivatives contract or repurchase agreement, the borrower of a portfolio's securities, or other obligation, will be unable or unwilling to make timely principal, interest, or settlement payments, or otherwise to honor its obligations.    Derivatives Risk. Transactions in derivatives (such as options, futures, currency contracts, and swaps) may increase volatility, cause the liquidation of portfolio positions when not advantageous to do so and produce disproportionate losses. Exchange-Traded Funds ("ETFs") Risk. An ETF is subject to the risks associated with direct ownership of the securities comprising the index on which the ETF is based. Fund shareholders indirectly bear their proportionate share of the expenses of the ETFs in which the fund invests.    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations.    High Yield Securities Risk. High yield fixed-income securities (commonly referred to as "junk bonds") are subject to greater credit quality risk than higher rated fixed-income securities and should be considered speculative.    Inverse Floating Rate Investments. Inverse floating rate investments are extremely sensitive to changes in interest rates and in some cases their market value may be extremely volatile. Leverage Risk. Leverage created by borrowing or certain types of transactions or investments, such as reverse repurchase agreements, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions, or derivative instruments, may impair the fund's liquidity, cause it to liquidate positions at an unfavorable time, increase volatility of the fund's net asset value, or diminish the fund's performance.    Municipal Securities Risk. Principal and interest payments on municipal securities may not be guaranteed by the issuing body and may be payable only from a particular source. That source may not perform as expected and payment obligations may not be made or made on time.    Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates. U.S. Government Securities Risk. Yields available from U.S. government securities are generally lower than yields from many other fixed-income securities.    U.S. Government Sponsored Securities Risk. Securities issued by U.S. government-sponsored or -chartered enterprises such as the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association, and the Federal Home Loan Banks are not issued or guaranteed by the U.S. Treasury.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance information is shown because the Fund has not yet had a calendar year of performance. The Fund's performance will be benchmarked against the Barclays Capital Municipal Bond Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance information is shown because the Fund has not yet had a calendar year of performance.
Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	3.75%
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.51%	[1],[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.26%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.29%)	[3]
Total Annual Fund Operating Expenses after Expense Reimbursement	rr_NetExpensesOverAssets	0.97%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	470
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	732
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	470
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	732
Opportunistic Municipal Fund (Prospectus Summary) | Opportunistic Municipal Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.54%	[1],[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.04%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.32%)	[3]
Total Annual Fund Operating Expenses after Expense Reimbursement	rr_NetExpensesOverAssets	1.72%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	275
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	609
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	175
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	609

[1] Other Expenses are estimated for the year ending August 31, 2012.

[2] Other Expenses include: Interest Expense 0.07%

[3] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class A and Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 0.90% for Class A and 1.65% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund

Small-MidCap Dividend Income Fund

Objective:

The Fund primarily seeks to provide a relatively high level of current income and
long-term growth of income

and secondarily long-term growth of capital, while investing primarily in small-
to mid-capitalization companies.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund. Information about discounts is available from your financial
professional and in "Choosing a Share Class and The Costs of Investing"
beginning on page 38 of the Fund's prospectus and "Multiple Class Structure"
beginning on page 59 of the Fund's Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Small-MidCap Dividend Income Fund Class C
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Small-MidCap Dividend Income Fund Class C
Management Fees		0.80%
Distribution and/or Service (12b-1) Fees		1.00%
Other Expenses	[1]	0.39%
Total Annual Fund Operating Expenses		2.19%
Expense Reimbursement	[2]	0.04%
Total Annual Fund Operating Expenses after Expense Reimbursement		2.15%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Small-MidCap Dividend Income Fund Class C	318	681

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years
Small-MidCap Dividend Income Fund Class C	218	681

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.
From June 6, 2011, date operations commenced, through August 31, 2011, the Fund's
annualized portfolio turnover rate was 43.5% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets,
plus borrowings for investment purposes, in dividend-paying equity securities
of companies with small to medium market capitalizations (those with market
capitalizations ranging from between $200 million and $7 billion) at the time
of purchase. The Fund invests in value equity securities, an investment strategy
that emphasizes buying equity securities that appear to be undervalued. The Fund
will invest in the securities of foreign issuers, real estate investment trusts,
preferred securities, convertible securities, fixed-income securities, master
limited partnerships, and royalty trusts.

Principal Risks

The Fund may be an appropriate investment for investors who seek dividends to
generate income or to reinvest for growth and who can accept fluctuations in the
value of investments and the risks of investing in real estate investment trust
securities and foreign securities.
  
The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:
  
Convertible Securities Risk. Convertible securities can be bonds, notes,
debentures, preferred stock or other securities which are convertible into
common stock. Convertible securities are subject to both the credit and interest
rate risks associated with fixed income securities and to the stock market risk
associated with equity securities.
  
Equity Securities Risk. Equity securities (common, convertible preferred stocks
and other securities whose values are tied to the price of stocks, such as rights,
warrants and convertible debt securities) could decline in value if the issuer's
financial condition declines or in response to overall market and economic conditions.
A fund's principal market segment(s), such as large cap, mid cap or small cap stocks,
or growth or value stocks, may underperform other market segments or the equity
markets as a whole. Investments in smaller companies and mid-size companies may
involve greater risk and price volatility than investments in larger, more mature
companies.
  
Fixed-Income Securities Risk. Fixed-income securities are subject to interest
rate risk and credit quality risk. The market value of fixed-income securities
generally declines when interest rates rise, and an issuer of fixed-income
securities could default on its payment obligations.
  
Foreign Securities Risk. The risks of foreign securities include loss of value
as a result of: political or economic instability; nationalization, expropriation
or confiscatory taxation; changes in foreign exchange rates and foreign exchange
restrictions; settlement delays; and limited government regulation (including less
stringent reporting, accounting, and disclosure standards than are required of
U.S. companies).
  
Master Limited Partnership ("MLP") Risk. MLPs are publicly-traded limited
partnership interests or units. An MLP that invests in a particular industry
(e.g., oil and gas) will be harmed by detrimental economic events within that
industry. As partnerships, MLPs may be subject to less regulation (and less
protection for investors) under state laws than corporations. In addition, MLPs
may be subject to state taxation in certain jurisdictions, which may reduce the
amount of income an MLP pays to its investors.
  
Preferred Securities Risk. Preferred securities are junior subordinated
securities in a company's capital structure and therefore can be subject to
greater credit and liquidation risk. An issuer of preferred securities could
redeem the security prior to the stated maturity date and reduce the return of
the security.
  
Real Estate Investment Trusts ("REITs") Risk. A REIT could fail to qualify for
tax-free pass-through of income under the Internal Revenue Code, and fund
shareholders will indirectly bear their proportionate share of the expenses
of REITs in which the fund invests.
  
Real Estate Securities Risk. Real estate securities are subject to the risks
associated with direct ownership of real estate, including declines in value,
adverse economic conditions, increases in expenses, regulatory changes and
environmental problems.

Risk of Being an Underlying Fund. An underlying fund of a fund of funds may
experience relatively large redemptions or investments as the fund of funds
periodically reallocates or rebalances its assets. These transactions may cause
the underlying fund to sell portfolio securities to meet such redemptions, or to
invest cash from such investments, at times it would not otherwise do so, and
may as a result increase transaction costs and adversely affect underlying fund
performance.
  
Royalty Trust Risk. A royalty trust generally acquires an interest in natural
resource or chemical companies and distributes the income it receives to its
investors. A sustained decline in demand for natural resource and related
products could adversely affect royalty trust revenues and cash flows. Such a
decline could result from a recession or other adverse economic conditions, an
increase in the market price of the underlying commodity, higher taxes or other
regulatory actions that increase costs, or a shift in consumer demand. Rising
interest rates could adversely affect the performance, and limit the capital
appreciation, of royalty trusts because of the increased availability of
alternative investments at more competitive yields. Fund shareholders will
indirectly bear their proportionate share of the royalty trusts' expenses.
  
Value Stock Risk. The market may not recognize the intrinsic value of value
stocks for a long time, or they may be appropriately priced at the time of
purchase.

Performance

No performance information is shown because the Fund has not yet had a calendar
year of performance. The Fund's performance will be benchmarked against the
Russell 2500 Value Index.

[1] Other Expenses estimated for the year ending August 31, 2012.

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.15% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Bond Market Index Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide current income.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	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	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 most recent fiscal year, the Fund's annualized portfolio turnover rate was 84.6% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	84.60%
Expenses, Restated to Reflect Current	rr_ExpensesRestatedToReflectCurrent	Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in debt securities held by the Barclays Capital U.S. Aggregate Bond Index (the "Index") at the time of purchase. The Index is composed of investment grade, fixed rate debt issues, including government, corporate, asset-backed, and mortgage-backed securities, with maturities of one year or more. The Fund employs a passive investment approach designed to attempt to track the performance of the Index. Under normal circumstances, the Fund maintains an average portfolio duration that is in line with the duration of the Barclays Capital U.S. Aggregate Bond Index, which as of August 31, 2011 was 5.05 years.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors interested in investing in a fixed-income mutual fund and preferring a passive, rather than active, management style.    The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations.    Index Fund Investment Risk. More likely than not, an index fund will not provide investment performance that matches the index performance due to cashflows and the fees and expenses of the fund. Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates.    Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed securities may have to be reinvested at lower rates. A reduction in prepayments may increase the effective maturities of these securities, exposing them to the risk of decline in market value over time (extension risk).    Real Estate Securities Risk. Real estate securities are subject to the risks associated with direct ownership of real estate, including declines in value, adverse economic conditions, increases in expenses, regulatory changes and environmental problems.    Risk of Being an Underlying Fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance. U.S. Government Securities Risk. Yields available from U.S. government securities are generally lower than yields from many other fixed-income securities.    U.S. Government Sponsored Securities Risk. Securities issued by U.S. government-sponsored or -chartered enterprises such as the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association, and the Federal Home Loan Banks are not issued or guaranteed by the U.S. Treasury.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The following information provides an indication of the risks of investing in the Fund. The bar chart shows the investment returns of the Fund's Class J shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund). These annual returns do not reflect sales charges; if they did, returns would be lower. The table shows, for Class J shares of the Fund and for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund's average annual total returns compare to the returns of one or more broad-based market indices. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You may get updated performance information online at www.principalfunds.com or by calling 1-800-222-5852.    Life of Fund returns are measured from the date the Class J shares were first sold December 30, 2009.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides an indication of the risks of investing in the Fund.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-222-5852
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.principalfunds.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Total Returns as of December 31 each year (Class J shares)	[1]
Bar Chart, Does Not Reflect Sales Loads	rr_BarChartDoesNotReflectSalesLoads	These annual returns do not reflect sales charges; if they did, returns would be lower.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Highest return for a quarter during the period of the bar chart above:  Q3 '11       3.60% Lowest return for a quarter during the period of the bar chart above:   Q4 '10      -1.49%
Performance Table, Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	These annual returns do not reflect sales charges; if they did, returns would be lower.
Index No Deduction for Fees, Expenses, Taxes	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction 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 and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an 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(k) plans or individual retirement accounts.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an 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(k) plans or individual retirement accounts.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns For the periods ended December 31, 2011
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund | Barclays Capital Aggregate Bond Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Barclays Capital Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	7.84%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	7.09%
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund | Class J Shares
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.45%
Other Expenses	rr_OtherExpensesOverAssets	0.35%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.05%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.20%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.85%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2012-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	187
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	314
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	560
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,265
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	87
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	314
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	560
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,265
Annual Return 2010	rr_AnnualReturn2010	4.80%
Annual Return 2011	rr_AnnualReturn2011	6.77%
Year to Date Return, Label	rr_YearToDateReturnLabel	The year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.09%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest return for a quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2011
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.60%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest return for a quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2010
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(1.49%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return Before Taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	5.77%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	5.72%
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund | Class J Shares | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return After Taxes on Distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	5.06%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	5.08%
Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund | Class J Shares | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class J Return After Taxes on Distribution and Sale of Fund Shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	3.75%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	4.51%

[1] The year-to-date return as of March 31, 2012 was 0.09% for Class J shares.

[2] Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.

[3] Effective January 1, 2012, Principal Funds Distributor, Inc. ("the Distributor") has contractually agreed to limit the Distribution Fees attributable to Class J through December 31, 2012. The limit will maintain the level of Distribution Fees not to exceed 0.25%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and the Distributor, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

XML

Bond Market Index Fund (Prospectus Summary) | Bond Market Index Fund

Bond Market Index Fund

Objective:

The Fund seeks to provide current income.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Bond Market Index Fund Class J Shares
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Bond Market Index Fund Class J Shares
Management Fees		0.25%
Distribution and/or Service (12b-1) Fees		0.45%
Other Expenses	[1]	0.35%
Total Annual Fund Operating Expenses		1.05%
Fee Waiver	[2]	0.20%
Total Annual Fund Operating Expenses After Fee Waiver		0.85%

Example

This Example is intended to help you compare the cost of investing in 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 of 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 remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years	Expense Example, With Redemption, 5 Years	Expense Example, With Redemption, 10 Years
Bond Market Index Fund Class J Shares	187	314	560	1,265

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years	Expense Example, No Redemption, 5 Years	Expense Example, No Redemption, 10 Years
Bond Market Index Fund Class J Shares	87	314	560	1,265

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 most recent fiscal year, the Fund's annualized portfolio turnover
rate was 84.6% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets,
plus borrowings for investment purposes, in debt securities held by the Barclays
Capital U.S. Aggregate Bond Index (the "Index") at the time of purchase. The
Index is composed of investment grade, fixed rate debt issues, including
government, corporate, asset-backed, and mortgage-backed securities, with
maturities of one year or more. The Fund employs a passive investment approach
designed to attempt to track the performance of the Index. Under normal
circumstances, the Fund maintains an average portfolio duration that is in line
with the duration of the Barclays Capital U.S. Aggregate Bond Index, which as of
August 31, 2011 was 5.05 years.

Principal Risks

The Fund may be an appropriate investment for investors interested in investing
in a fixed-income mutual fund and preferring a passive, rather than active,
management style.
  
The value of your investment in the Fund changes with the value of the Fund's
investments. Many factors affect that value, and it is possible to lose money by
investing in the Fund. An investment in the Fund is not a deposit of a bank and
is not insured or guaranteed by the Federal Deposit Insurance Corporation or any
other government agency. The principal risks of investing in the Fund, in
alphabetical order, are:
  
Fixed-Income Securities Risk. Fixed-income securities are subject to interest
rate risk and credit quality risk. The market value of fixed-income securities
generally declines when interest rates rise, and an issuer of fixed-income
securities could default on its payment obligations.
  
Index Fund Investment Risk. More likely than not, an index fund will not provide
investment performance that matches the index performance due to cashflows and
the fees and expenses of the fund.

Portfolio Duration Risk. Portfolio duration is a measure of the expected life of
a fixed-income security and its sensitivity to changes in interest rates. The
longer a fund's average portfolio duration, the more sensitive the fund will be
to changes in interest rates.
  
Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed
securities may have to be reinvested at lower rates. A reduction in prepayments
may increase the effective maturities of these securities, exposing them to the
risk of decline in market value over time (extension risk).
  
Real Estate Securities Risk. Real estate securities are subject to the risks
associated with direct ownership of real estate, including declines in value,
adverse economic conditions, increases in expenses, regulatory changes and
environmental problems.
  
Risk of Being an Underlying Fund. An underlying fund of a fund of funds may
experience relatively large redemptions or investments as the fund of funds
periodically reallocates or rebalances its assets. These transactions may cause
the underlying fund to sell portfolio securities to meet such redemptions, or to
invest cash from such investments, at times it would not otherwise do so, and
may as a result increase transaction costs and adversely affect underlying fund
performance.

U.S. Government Securities Risk. Yields available from U.S. government
securities are generally lower than yields from many other fixed-income
securities.
  
U.S. Government Sponsored Securities Risk. Securities issued by U.S.
government-sponsored or -chartered enterprises such as the Federal Home Loan
Mortgage Corporation, the Federal National Mortgage Association, and the Federal
Home Loan Banks are not issued or guaranteed by the U.S. Treasury.

Performance

The following information provides an indication of the risks of investing in
the Fund. The bar chart shows the investment returns of the Fund's Class J
shares for each full calendar year of operations for 10 years (or, if shorter,
the life of the Fund). These annual returns do not reflect sales charges; if
they did, returns would be lower. The table shows, for Class J shares of the
Fund and for the last one, five, and ten calendar year periods (or, if shorter,
the life of the Fund), how the Fund's average annual total returns compare to
the returns of one or more broad-based market indices. Past performance (before
and after taxes) is not necessarily an indication of how the Fund will perform
in the future. You may get updated performance information online at
www.principalfunds.com or by calling 1-800-222-5852.
  
Life of Fund returns are measured from the date the Class J shares were first
sold December 30, 2009.

Total Returns as of December 31 each year (Class J shares)

^[1]

Highest return for a quarter during the period of the bar chart above:  Q3 '11       3.60%
Lowest return for a quarter during the period of the bar chart above:   Q4 '10      -1.49%

Average Annual Total Returns For the periods ended December 31, 2011

Average Annual Total Returns Bond Market Index Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, Since Inception
Class J Shares	Class J Return Before Taxes	5.77%	5.72%
Class J Shares After Taxes on Distributions	Class J Return After Taxes on Distributions	5.06%	5.08%
Class J Shares After Taxes on Distributions and Sales	Class J Return After Taxes on Distribution and Sale of Fund Shares	3.75%	4.51%
Barclays Capital Aggregate Bond Index	Barclays Capital Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	7.09%

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of state and local taxes.
Actual after-tax returns depend on an 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(k) plans or
individual retirement accounts.

[1] Expense information has been restated to reflect current fees. Certain Other Expenses of the Fund have increased effective November 1, 2011.

[2] Effective January 1, 2012, Principal Funds Distributor, Inc. ("the Distributor") has contractually agreed to limit the Distribution Fees attributable to Class J through December 31, 2012. The limit will maintain the level of Distribution Fees not to exceed 0.25%. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and the Distributor, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

[1] The year-to-date return as of March 31, 2012 was 0.09% for Class J shares.