1.0.0.3 false Statement Of Financial Position Unclassified - Deposit Based Operations (USD $) In Millions false 1 $ false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 shares Standard http://www.xbrl.org/2003/instance shares 0 false 2 $ false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 shares Standard http://www.xbrl.org/2003/instance shares 0 5 3 us-gaap_AssetsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 6 4 us-gaap_CashAndDueFromBanks us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 true true 2641000000 2641 false false 2 true true 3181000000 3181 false false No definition available. No authoritative reference available. false 7 4 us-gaap_InterestBearingDepositsInBanks us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 26632000000 26632 false false 2 false true 55733000000 55733 false false No definition available. No authoritative reference available. false 8 4 us-gaap_SecuritiesPurchasedUnderAgreementsToResell us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 2387000000 2387 false false 2 false true 1635000000 1635 false false No definition available. No authoritative reference available. false 9 4 us-gaap_TradingAccountAssetsFairValueDisclosure us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 148000000 148 false false 2 false true 815000000 815 false false No definition available. No authoritative reference available. false 10 4 us-gaap_AvailableForSaleSecurities us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 72699000000 72699 false false 2 false true 54163000000 54163 false false No definition available. No authoritative reference available. false 11 4 stt_HeldToMaturityInvestmentSecuritiesPurchasedUnderMoneyMarketLiquidityFacility stt false debit instant monetary Held-To-maturity investment securities purchased at amortized cost under Asset-Backed Commercial Paper Money Market Mutual... false false false false false false false false false 1 false true 0 0 false false 2 false true 6087000000 6087 false false Held-To-maturity investment securities purchased at amortized cost under Asset-Backed Commercial Paper Money Market Mutual Fund Liquidity Facility instituted by the Federal Reserve Bank of Boston. No authoritative reference available. false 12 4 us-gaap_HeldToMaturitySecurities us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 20877000000 20877 false false 2 false true 15767000000 15767 false false No definition available. No authoritative reference available. false 13 4 us-gaap_LoansAndLeasesReceivableNetReportedAmount us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 10729000000 10729 false false 2 false true 9113000000 9113 false false No definition available. No authoritative reference available. false 14 4 us-gaap_PropertyPlantAndEquipmentNet us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 1953000000 1953 false false 2 false true 2011000000 2011 false false No definition available. No authoritative reference available. false 15 4 us-gaap_AccruedInvestmentIncomeReceivable us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 1497000000 1497 false false 2 false true 1738000000 1738 false false No definition available. No authoritative reference available. false 16 4 us-gaap_Goodwill us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 4550000000 4550 false false 2 false true 4527000000 4527 false false No definition available. No authoritative reference available. false 17 4 us-gaap_IntangibleAssetsNetExcludingGoodwill us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 1810000000 1810 false false 2 false true 1851000000 1851 false false No definition available. No authoritative reference available. false 18 4 us-gaap_OtherAssets us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 12023000000 12023 false false 2 false true 17010000000 17010 false false No definition available. No authoritative reference available. false 19 4 us-gaap_Assets us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 157946000000 157946 false false 2 false true 173631000000 173631 false false No definition available. No authoritative reference available. true 21 4 us-gaap_DepositsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 22 5 us-gaap_NoninterestBearingDepositLiabilities us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 11969000000 11969 false false 2 false true 32785000000 32785 false false No definition available. No authoritative reference available. false 23 5 us-gaap_InterestBearingDepositLiabilitiesDomestic us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 5956000000 5956 false false 2 false true 4558000000 4558 false false No definition available. No authoritative reference available. false 24 5 us-gaap_InterestBearingDepositLiabilitiesForeign us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 72137000000 72137 false false 2 false true 74882000000 74882 false false No definition available. No authoritative reference available. false 25 5 us-gaap_Deposits us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 90062000000 90062 false false 2 false true 112225000000 112225 false false No definition available. No authoritative reference available. true 26 4 us-gaap_SecuritiesSoldUnderAgreementsToRepurchase us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 10542000000 10542 false false 2 false true 11154000000 11154 false false No definition available. No authoritative reference available. false 27 4 us-gaap_FederalFundsPurchased us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 4532000000 4532 false false 2 false true 1082000000 1082 false false No definition available. No authoritative reference available. false 28 4 stt_ShortTermBorrowingsUnderMoneyMarketLiquidityFacility stt false credit instant monetary Carrying value of short-term non-recourse borrowings associated with the Asset-Backed Commercial Paper Money Market Mutual... false false false false false false false false false 1 false true 0 0 false false 2 false true 6042000000 6042 false false Carrying value of short-term non-recourse borrowings associated with the Asset-Backed Commercial Paper Money Market Mutual Fund Liquidity Facility instituted by the Federal Reserve Bank of Boston. No authoritative reference available. false 29 4 us-gaap_OtherShortTermBorrowings us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 20200000000 20200 false false 2 false true 11555000000 11555 false false No definition available. No authoritative reference available. false 30 4 us-gaap_AccruedLiabilitiesCurrentAndNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 9281000000 9281 false false 2 false true 14380000000 14380 false false No definition available. No authoritative reference available. false 31 4 us-gaap_LongTermDebt us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 8838000000 8838 false false 2 false true 4419000000 4419 false false No definition available. No authoritative reference available. false 32 4 us-gaap_Liabilities us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 143455000000 143455 false false 2 false true 160857000000 160857 false false No definition available. No authoritative reference available. true 34 3 us-gaap_StockholdersEquityAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 35 4 us-gaap_PreferredStockValue us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 1883000000 1883 false false No definition available. No authoritative reference available. false 36 4 us-gaap_CommonStockValue us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 495000000 495 false false 2 false true 432000000 432 false false No definition available. No authoritative reference available. false 37 4 us-gaap_AdditionalPaidInCapital us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 9180000000 9180 false false 2 false true 6992000000 6992 false false No definition available. No authoritative reference available. false 38 4 us-gaap_RetainedEarningsAccumulatedDeficit us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 7071000000 7071 false false 2 false true 9135000000 9135 false false No definition available. No authoritative reference available. false 39 4 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true -2238000000 -2238 false false 2 false true -5650000000 -5650 false false No definition available. No authoritative reference available. false 40 4 us-gaap_TreasuryStockValue us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true -17000000 -17 false false 2 false true -18000000 -18 false false No definition available. No authoritative reference available. false 41 4 us-gaap_StockholdersEquity us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 14491000000 14491 false false 2 false true 12774000000 12774 false false No definition available. No authoritative reference available. true 42 3 us-gaap_LiabilitiesAndStockholdersEquity us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 true true 157946000000 157946 false false 2 true true 173631000000 173631 false false No definition available. No authoritative reference available. true false 2 36 false Millions UnKnown UnKnown false true