485BPOS

As filed with the Securities and Exchange Commission on December 20, 2012

Securities Act of 1933 File No. 333-173967

Investment Company Act of 1940 File No. 811-22555

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

          REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933                x

Pre-Effective Amendment No.           ¨

Post-Effective Amendment No. 31  x

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940  x

Amendment No. 33  x

(Check Appropriate Box or Boxes)

FLEXSHARES TRUST

(Exact Name of Registrant as Specified in Charter)

50 South LaSalle Street

Chicago, Illinois 60603

(Address of Principal Executive Offices)

800-595-9111

(Registrant’s Telephone Number, including Area Code)

Name and Address of Agent for Service:	with a copy to:
Diana E. McCarthy, Esq.	Peter K. Ewing
Drinker Biddle & Reath LLP	Craig R. Carberry, Esq.
One Logan Square, Ste. 2000	Northern Trust Investments, Inc.
Philadelphia, Pennsylvania 19103-6996	50 South LaSalle Street
	Chicago, Illinois 60603

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

x immediately upon filing pursuant to paragraph (b)

¨ on (date) pursuant to paragraph (b)

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

¨ on (date) pursuant to paragraph (a)(1)

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

¨ 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.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “Securities Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all the requirements for effectiveness of this Post-Effective Amendment No. 31 pursuant to Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 31 to its Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Chicago and State of Illinois on the 20^th day of December 2012.

FLEXSHARES TRUST
By:	/s/ Shundrawn A. Thomas
	Shundrawn A. Thomas
	Trustee and President

Pursuant to the requirements of the Securities Act, this Post-Effective Amendment No. 31 to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Name	Title	Date
* Sarah N. Garvey Sarah N. Garvey	Trustee	December 20, 2012
* Philip G. Hubbard Philip G. Hubbard	Trustee	December 20, 2012
* Eric T. McKissack Eric T. McKissack	Trustee	December 20, 2012
/s/ Shundrawn A. Thomas Shundrawn A. Thomas	Trustee and President (Principal Executive Officer)	December 20, 2012
/s/ Randal Rein Randal Rein	Treasurer (Principal Financial Officer and Principal Accounting Officer)	December 20, 2012

* By:	/s/ Diana E. McCarthy
	Diana E. McCarthy
	Attorney-In-Fact, pursuant to power of attorney

EXHIBIT INDEX

EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares International Quality Dividend Defensive Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® International Quality Dividend Defensive Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the Northern Trust International Quality Dividend Defensive IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility that is lower than that of the Northern Trust International Large Cap IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors , such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 0.5 to 1.0 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is lower than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares International Quality Dividend Defensive Index Fund | FlexShares International Quality Dividend Defensive Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.47%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.48%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.47%
1 Year	rr_ExpenseExampleYear01	48
3 Years	rr_ExpenseExampleYear03	153

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
Document Creation Date	dei_DocumentCreationDate	Dec. 10, 2012

XML

FlexShares Quality Dividend Index Fund

FlexShares^® Quality Dividend Index Fund

Investment Objective

The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares Quality Dividend Index 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		FlexShares Quality Dividend Index Fund
Management Fees		0.37%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.38%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.37%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares Quality Dividend Index Fund
1 Year	38
3 Years	121

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility similar to that of the Northern Trust 1250 Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta similar to the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is similar to that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares Quality Dividend Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® Quality Dividend Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility similar to that of the Northern Trust 1250 IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta similar to the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is similar to that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares Quality Dividend Index Fund | FlexShares Quality Dividend Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.37%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.38%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.37%
1 Year	rr_ExpenseExampleYear01	38
3 Years	rr_ExpenseExampleYear03	121

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

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FlexShares International Quality Dividend Dynamic Index Fund

FlexShares^® International Quality Dividend Dynamic Index Fund

Investment Objective

The Fund seeks to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the Northern Trust International Quality Dividend Dynamic Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares International Quality Dividend Dynamic Index 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		FlexShares International Quality Dividend Dynamic Index Fund
Management Fees		0.47%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.48%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.47%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares International Quality Dividend Dynamic Index Fund
1 Year	48
3 Years	153

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility that is greater than that of the Northern Trust International Large Cap Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors , such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 1.0 to 1.5 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be lower or greater than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is greater than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility lower or greater than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

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FlexShares Quality Dividend Dynamic Index Fund

FlexShares^® Quality Dividend Dynamic Index Fund

Investment Objective

The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend Dynamic Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares Quality Dividend Dynamic Index 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		FlexShares Quality Dividend Dynamic Index Fund
Management Fees		0.37%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.38%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.37%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares Quality Dividend Dynamic Index Fund
1 Year	38
3 Years	121

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility that is greater than that of the Northern Trust 1250 Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 1.0 to 1.5 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is greater than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

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FlexShares International Quality Dividend Index Fund

FlexShares^® International Quality Dividend Index Fund

Investment Objective

The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust International Quality Dividend Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares International Quality Dividend Index 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		FlexShares International Quality Dividend Index Fund
Management Fees		0.47%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.48%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.47%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares International Quality Dividend Index Fund
1 Year	48
3 Years	153

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility similar to that of the Northern Trust International Large Cap Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta similar to that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is similar to that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

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Document and Entity Information	12 Months Ended
	Dec. 10, 2012
Risk/Return:
Document Type	485BPOS
Document Period End Date	Dec. 10, 2012
Registrant Name	FlexShares Trust
Central Index Key	0001491978
Amendment Flag	false
Document Creation Date	Dec. 10, 2012
Document Effective Date	Dec. 10, 2012
Prospectus Date	Dec. 10, 2012

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FlexShares Quality Dividend Defensive Index Fund

FlexShares^® Quality Dividend Defensive Index Fund

Investment Objective

The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend Defensive Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares Quality Dividend Defensive Index 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		FlexShares Quality Dividend Defensive Index Fund
Management Fees		0.37%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.38%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.37%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares Quality Dividend Defensive Index Fund
1 Year	38
3 Years	121

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility that is lower than that of the Northern Trust 1250 Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 0.5 to 1.0 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is lower than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares Quality Dividend Dynamic Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® Quality Dividend Dynamic Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend Dynamic IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility that is greater than that of the Northern Trust 1250 IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 1.0 to 1.5 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is greater than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares Quality Dividend Dynamic Index Fund | FlexShares Quality Dividend Dynamic Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.37%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.38%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.37%
1 Year	rr_ExpenseExampleYear01	38
3 Years	rr_ExpenseExampleYear03	121

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares Quality Dividend Defensive Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® Quality Dividend Defensive Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust Quality Dividend Defensive IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of U.S. equity securities, with an emphasis on long-term capital growth and a targeted overall volatility that is lower than that of the Northern Trust 1250 IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 0.5 to 1.0 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of the 1250 largest U.S. domiciled companies by market capitalization. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, options and swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is lower than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than that of the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares Quality Dividend Defensive Index Fund | FlexShares Quality Dividend Defensive Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.37%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.38%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.37%
1 Year	rr_ExpenseExampleYear01	38
3 Years	rr_ExpenseExampleYear03	121

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares International Quality Dividend Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® International Quality Dividend Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust International Quality Dividend IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility similar to that of the Northern Trust International Large Cap IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors, such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta similar to that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is similar to that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares International Quality Dividend Index Fund | FlexShares International Quality Dividend Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.47%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.48%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.47%
1 Year	rr_ExpenseExampleYear01	48
3 Years	rr_ExpenseExampleYear03	153

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FlexShares Trust
Prospectus Date	rr_ProspectusDate	Dec. 10, 2012
FlexShares International Quality Dividend Dynamic Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FlexShares® International Quality Dividend Dynamic Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the Northern Trust International Quality Dividend Dynamic IndexSM (the “Underlying Index”).
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 10, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility that is greater than that of the Northern Trust International Large Cap IndexSM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors , such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 1.0 to 1.5 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions. NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued. NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund. The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index. The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease. Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates. Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested. Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets. Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes. Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline. Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry. Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value. Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results. Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares. Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets. Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be lower or greater than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is greater than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility lower or greater than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility. It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Fund Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund has less than one full calendar year of performance, no performance information has been included.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund has less than one full calendar year of performance, no performance information has been included.
FlexShares International Quality Dividend Dynamic Index Fund | FlexShares International Quality Dividend Dynamic Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.47%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.48%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.47%
1 Year	rr_ExpenseExampleYear01	48
3 Years	rr_ExpenseExampleYear03	153

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.

XML

FlexShares International Quality Dividend Defensive Index Fund

FlexShares^® International Quality Dividend Defensive Index Fund

Investment Objective

The Fund seeks to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the Northern Trust International Quality Dividend Defensive Index^SM (the “Underlying Index”).

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 will also incur usual and customary brokerage commissions when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	FlexShares International Quality Dividend Defensive Index 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		FlexShares International Quality Dividend Defensive Index Fund
Management Fees		0.47%
Distribution (12b-1) Fees		none
Other Expenses	[1]	0.01%
Total Annual Fund Operating Expenses		0.48%
Expense Reimbursement	[2]	(0.01%)
Total Annual Fund Operating Expenses After Expense Reimbursement		0.47%

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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 (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	FlexShares International Quality Dividend Defensive Index Fund
1 Year	48
3 Years	153

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. Portfolio turnover may vary from year to year, as well as within a year.

Principal Investment Strategies

The Underlying Index is designed to provide exposure to a high-quality, income-oriented portfolio of international equity securities issued by non-U.S.-based companies, with an emphasis on long-term capital growth and a targeted overall volatility that is lower than that of the Northern Trust International Large Cap Index^SM (the “Parent Index”). Companies included in the Underlying Index are a subset of the Parent Index, and are selected based on expected dividend payment and fundamental factors , such as profitability, solid management and reliable cash flow, as determined by NTI (in its capacity as the index provider (the “Index Provider”)), pursuant to its index methodology. The Underlying Index is designed to outperform the Parent Index on a risk-adjusted basis, with respect to a combination of dividend yield and capital appreciation. The Underlying Index begins with the Parent Index, and then follows a rules-based methodology to calculate optimal weights for securities in the Underlying Index based upon a targeted overall beta generally between 0.5 to 1.0 times that of the Parent Index, dividend yield, quality factors and lower total risk. Beta represents the market sensitivity, relative to a given market index and time period, and is one measure of volatility. The Parent Index is a float-adjusted market capitalization weighted index comprised of eligible large capitalization securities of developed or emerging market countries as determined by the Index Provider, pursuant to its index methodology. In addition to tracking the performance of the Underlying Index, the Investment Adviser seeks to minimize portfolio turnover and tax inefficiencies. The Underlying Index is governed by transparent, objective rules for security selection, exclusion, rebalancing and adjustments for corporate actions.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” its Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. Securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. Funds that employ a representative sampling strategy may incur tracking error risk to a greater extent than a fund that seeks to replicate an index. “Replication” is an indexing strategy in which a fund invests in substantially all of the securities in its underlying index in approximately the same proportions as in the underlying index. The Fund reserves the right to use a replication indexing strategy if NTI determines that it is in the best interests of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets in the securities of the Underlying Index and in American Depositary Receipts (“ADRs”) and Global Depositary Receipts (“GDRs”) (collectively “Depositary Receipts”) based on the securities in its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts, options on futures contracts, foreign currency contracts, options and total return swaps, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is sponsored by the Index Provider. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Index is reconstituted quarterly. Additional information regarding the Index Provider is provided in the “More Information about Underlying Indexes and Index Provider” section of the Prospectus.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Counterparty Risk is the risk that a counterparty to a financial instrument may default on its payment obligation to the Fund. Such a default may cause the value of an investment in the Fund to decrease.

Currency Risk is the risk that foreign currencies will fluctuate in value relative to the U.S. dollar, adversely affecting the value of the Fund’s investments and its returns. Because the Fund’s NAV is determined on the basis of U.S. dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the market value of the Fund’s holdings appreciates.

Derivatives Risk is the risk of investing in derivative instruments, including liquidity, interest rate, market, credit and management risks, mispricing or improper valuation. Changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund could lose more than the principal amount invested.

Dividend Risk is the risk that an issuer of stock held by the Fund may choose not to declare a dividend or the dividend rate might not remain at current levels. Dividend paying stocks might not experience the same level of earnings growth or capital appreciation as non-dividend paying stocks. The Fund’s performance during a broad market advance could suffer because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks.

Emerging Markets Risk is the risk that markets of emerging market countries are less developed and less liquid, subject to greater price volatility and generally subject to increased economic, political, regulatory and other uncertainties than more developed markets.

Equity Securities Risk is the risk that the values of the equity securities owned by the Fund may be more volatile than other asset classes.

Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in U.S. securities, due to less liquid markets, and adverse economic, political, diplomatic, financial and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. To the extent that the Fund’s assets may be concentrated in a single country or countries located in the same geographic region, the Fund will be subject to risks associated with that particular country or region, such as general and local economic, political and social conditions. Any of these events could cause the value of the Fund’s investments to decline.

Industry Concentration Risk is the risk that, to the extent the Fund’s investments are concentrated in the securities of issuers in a particular industry, the Fund may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that industry.

Issuer Risk is the risk that changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Management Risk is the risk that the representative sampling strategy used by NTI may fail to produce the intended results.

Market Risk is the risk that the Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risks are the risks that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

New Fund Risks are the risks that the Fund faces because it is a new fund. As a new fund, there can be no assurance that it will grow to or maintain an economically viable size, in which case it may experience greater tracking error to its Underlying Index than it otherwise would at higher asset levels, or it could ultimately liquidate. The Fund’s Distributor does not maintain a secondary market in the shares.

Passive Investment Risk is the risk that the Fund is not actively managed and NTI does not attempt to take defensive positions in any market conditions, including declining markets.

Tracking Error Risk is the risk that the Fund’s performance may vary substantially from the performance of the Underlying Index. The Fund employs a representative sampling strategy, and may incur tracking error risk to a greater extent than a fund that seeks to replicate an index.

Volatility Risk is the risk that the actual level of volatility experienced by the Fund may be greater or lower than the targeted overall volatility of the Underlying Index. Although the Underlying Index is designed to have a targeted overall volatility that is lower than that of the Parent Index, there is no guarantee that it will have the targeted overall volatility. The Fund will continue to seek to track the Underlying Index even if the Underlying Index does not have the targeted overall volatility. There is also the risk that the Fund may experience volatility greater or lower than the Underlying Index as a result of tracking error. A portfolio of securities with greater volatility is generally considered to have a higher risk profile than a portfolio with lower volatility.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

Because the Fund has less than one full calendar year of performance, no performance information has been included.

[1] Under the Fund's Investment Advisory Agreement, Northern Trust Investments, Inc. ("NTI" or "Investment Adviser") is responsible for most of the operating expenses of the Fund. However, the Investment Adviser is not responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. Other Expenses are estimated as the Fund had not commenced operations as of December 10, 2012.

[2] NTI has contractually agreed to reimburse the fees and expenses of the Trust's independent trustees and their independent legal counsel until December 10, 2013. The Fund's Board of Trustees may terminate the contractual arrangement at any time if it determines that it is in the best interest of the Fund and its shareholders.