3.22.4 html 179 77 1 true 109 0 false 2 false false R1.htm 000000 - Document - Document and Entity Information {Elements} Sheet http://www.flexshares.com/role/DocumentDocumentandEntityInformationElements000000 Document and Entity Information 1 false false R2.htm 000021 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares US Quality Low Volatility Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesUSQualityLowVolatilityIndexFund000021 Risk/Return Detail Data- FlexShares US Quality Low Volatility Index Fund 2 false false R3.htm 000041 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Developed Markets ex-US Quality Low Volatility Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesDevelopedMarketsex-USQualityLowVolatilityIndexFund000041 Risk/Return Detail Data- FlexShares Developed Markets ex-US Quality Low Volatility Index Fund 3 false false R4.htm 000061 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Emerging Markets Quality Low Volatility Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesEmergingMarketsQualityLowVolatilityIndexFund000061 Risk/Return Detail Data- FlexShares Emerging Markets Quality Low Volatility Index Fund 4 false false R5.htm 000081 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Morningstar US Market Factor Tilt Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesMorningstarUSMarketFactorTiltIndexFund000081 Risk/Return Detail Data- FlexShares Morningstar US Market Factor Tilt Index Fund 5 false false R6.htm 000101 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Morningstar Developed Markets ex-US Factor Tilt Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesMorningstarDevelopedMarketsex-USFactorTiltIndexFund000101 Risk/Return Detail Data- FlexShares Morningstar Developed Markets ex-US Factor Tilt Index Fund 6 false false R7.htm 000121 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Morningstar Emerging Markets Factor Tilt Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesMorningstarEmergingMarketsFactorTiltIndexFund000121 Risk/Return Detail Data- FlexShares Morningstar Emerging Markets Factor Tilt Index Fund 7 false false R8.htm 000141 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares US Quality Large Cap Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesUSQualityLargeCapIndexFund000141 Risk/Return Detail Data- FlexShares US Quality Large Cap Index Fund 8 false false R9.htm 000161 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares STOXX US ESG Select Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesSTOXXUSESGSelectIndexFund000161 Risk/Return Detail Data- FlexShares STOXX US ESG Select Index Fund 9 false false R10.htm 000181 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares STOXX Global ESG Select Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesSTOXXGlobalESGSelectIndexFund000181 Risk/Return Detail Data- FlexShares STOXX Global ESG Select Index Fund 10 false false R11.htm 000201 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares ESG & Climate US Large Cap Core Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesESGClimateUSLargeCapCoreIndexFund Risk/Return Detail Data- FlexShares ESG & Climate US Large Cap Core Index Fund 11 false false R12.htm 000221 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares ESG & Climate Developed Markets ex-US Core Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesESGClimateDevelopedMarketsexUSCoreIndexFund Risk/Return Detail Data- FlexShares ESG & Climate Developed Markets ex-US Core Index Fund 12 false false R13.htm 000241 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares ESG & Climate Emerging Markets Core Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesESGClimateEmergingMarketsCoreIndexFund Risk/Return Detail Data- FlexShares ESG & Climate Emerging Markets Core Index Fund 13 false false R14.htm 000261 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Morningstar Global Upstream Natural Resources Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesMorningstarGlobalUpstreamNaturalResourcesIndexFund000261 Risk/Return Detail Data- FlexShares Morningstar Global Upstream Natural Resources Index Fund 14 false false R15.htm 000281 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares STOXX Global Broad Infrastructure Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesSTOXXGlobalBroadInfrastructureIndexFund000281 Risk/Return Detail Data- FlexShares STOXX Global Broad Infrastructure Index Fund 15 false false R16.htm 000301 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Global Quality Real Estate Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesGlobalQualityRealEstateIndexFund000301 Risk/Return Detail Data- FlexShares Global Quality Real Estate Index Fund 16 false false R17.htm 000321 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Real Assets Allocation Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesRealAssetsAllocationIndexFund000321 Risk/Return Detail Data- FlexShares Real Assets Allocation Index Fund 17 false false R18.htm 000341 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Quality Dividend Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesQualityDividendIndexFund000341 Risk/Return Detail Data- FlexShares Quality Dividend Index Fund 18 false false R19.htm 000361 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Quality Dividend Defensive Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesQualityDividendDefensiveIndexFund000361 Risk/Return Detail Data- FlexShares Quality Dividend Defensive Index Fund 19 false false R20.htm 000381 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Quality Dividend Dynamic Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesQualityDividendDynamicIndexFund000381 Risk/Return Detail Data- FlexShares Quality Dividend Dynamic Index Fund 20 false false R21.htm 000401 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares International Quality Dividend Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesInternationalQualityDividendIndexFund000401 Risk/Return Detail Data- FlexShares International Quality Dividend Index Fund 21 false false R22.htm 000421 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares International Quality Dividend Defensive Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesInternationalQualityDividendDefensiveIndexFund000421 Risk/Return Detail Data- FlexShares International Quality Dividend Defensive Index Fund 22 false false R23.htm 000441 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares International Quality Dividend Dynamic Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesInternationalQualityDividendDynamicIndexFund000441 Risk/Return Detail Data- FlexShares International Quality Dividend Dynamic Index Fund 23 false false R24.htm 000461 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares iBoxx 3-Year Target Duration TIPS Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesiBoxx3-YearTargetDurationTIPSIndexFund000461 Risk/Return Detail Data- FlexShares iBoxx 3-Year Target Duration TIPS Index Fund 24 false false R25.htm 000481 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares iBoxx 5-Year Target Duration TIPS Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesiBoxx5-YearTargetDurationTIPSIndexFund000481 Risk/Return Detail Data- FlexShares iBoxx 5-Year Target Duration TIPS Index Fund 25 false false R26.htm 000501 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Disciplined Duration MBS Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesDisciplinedDurationMBSIndexFund000501 Risk/Return Detail Data- FlexShares Disciplined Duration MBS Index Fund 26 false false R27.htm 000521 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Credit-Scored US Corporate Bond Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesCredit-ScoredUSCorporateBondIndexFund000521 Risk/Return Detail Data- FlexShares Credit-Scored US Corporate Bond Index Fund 27 false false R28.htm 000541 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Credit-Scored US Long Corporate Bond Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesCredit-ScoredUSLongCorporateBondIndexFund000541 Risk/Return Detail Data- FlexShares Credit-Scored US Long Corporate Bond Index Fund 28 false false R29.htm 000561 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares High Yield Value-Scored Bond Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesHighYieldValue-ScoredBondIndexFund000561 Risk/Return Detail Data- FlexShares High Yield Value-Scored Bond Index Fund 29 false false R30.htm 000581 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares ESG & Climate High Yield Corporate Core Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesESGClimateHighYieldCorporateCoreIndexFund Risk/Return Detail Data- FlexShares ESG & Climate High Yield Corporate Core Index Fund 30 false false R31.htm 000601 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares ESG & Climate Investment Grade Corporate Core Index Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesESGClimateInvestmentGradeCorporateCoreIndexFund Risk/Return Detail Data- FlexShares ESG & Climate Investment Grade Corporate Core Index Fund 31 false false R32.htm 000621 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Ready Access Variable Income Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesReadyAccessVariableIncomeFund000621 Risk/Return Detail Data- FlexShares Ready Access Variable Income Fund 32 false false R33.htm 000641 - Disclosure - Risk/Return Detail Data {Elements} - FlexShares Core Select Bond Fund Sheet http://www.flexshares.com/role/DisclosureRiskReturnDetailDataElementsFlexSharesCoreSelectBondFund000641 Risk/Return Detail Data- FlexShares Core Select Bond Fund 33 false false All Reports Book All Reports d380561d485bpos.htm d380561dex99a6.htm d380561dex99d6.htm d380561dex99d7.htm d380561dex99d8.htm d380561dex99e6.htm d380561dex99g6.htm d380561dex99h17.htm d380561dex99h7.htm d380561dex99h8.htm d380561dex99j.htm fst-20230227.xsd fst-20230227_cal.xml fst-20230227_def.xml fst-20230227_lab.xml fst-20230227_pre.xml g380561dsp001.jpg g380561dsp0025.jpg g380561dsp004.jpg g380561dsp0123.jpg g380561dsp024.jpg g380561dsp122.jpg g380561g2csuscbindex_16.jpg g380561g2ddmbsindex_15.jpg g380561g2dmxusqlvi_8.jpg g380561g2emqlvindex_7.jpg g380561g2esgcdmeusci_3.jpg g380561g2esgchycci_3.jpg g380561g2esgcigcci_3.jpg g380561g2esgcuslcci_3.jpg g380561g2fiveyeartarget_23.jpg g380561g2gblesgimpindex_11.jpg g380561g2glbbrdinfindex_17.jpg g380561g2glbqlrealestindex_1.jpg g380561g2hyvsbi_8.jpg g380561g2img35d5f2221.jpg g380561g2img7af754c13.jpg g380561g2imgc3b948b12.jpg g380561g2intlqdivdefindex_19.jpg g380561g2intlqdivdynindex_17.jpg g380561g2intlqdivindex_17.jpg g380561g2lrgcapindex_12.jpg g380561g2qdividenddef_19.jpg g380561g2qdividenddyn_19.jpg g380561g2qdividendindex_18.jpg g380561g2realassallindex_12.jpg g380561g2threeyeartarget_25.jpg g380561g2usesgimpindex_11.jpg g380561g2uslongcorpbond_12.jpg g380561g2usmarketfactortilt_.jpg g380561g2usqlvi_7.jpg g380561g2xyflex_logo.gif g380561g2xymanaged_nt.gif g380561g3csbfund_12.jpg g380561g3ravifund_20.jpg g380561g3xyflex_logo.gif g380561g3xymanaged_nt.gif http://xbrl.sec.gov/dei/2021 http://xbrl.sec.gov/rr/2021 true true