2.2.0.25truefalse40401 - Disclosure - Loans and Leases (Narrative) (Details)truefalsefalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011
USD ($)
USD ($) / shares
$Duration_1_1_2011_To_3_31_2011http://www.sec.gov/CIK0000093751duration2011-01-01T00:00:002011-03-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 3/31/2010
USD ($)
USD ($) / shares
$Duration_1_1_2010_To_3_31_2010http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-03-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDfalsefalse1/1/2010 - 12/31/2010
USD ($)
$Duration_1_1_2010_To_12_31_2010http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2false0us-gaap_BankOverdraftsus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse36400000003640000000falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse26300000002630000000falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date of payments made in excess of existing cash balances, which will be honored by the bank but reflected as a loan to the entity. Overdrafts generally have a very short time frame for correction or repayment and are therefore more similar to short-term bank financing than trade financing.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 7
falsefalse3false0stt_AggregateOfDebtRestructuringssttfalsecreditdurationAggregate of debt restructuringsfalsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse302000000302000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse307000000307000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAggregate of debt restructuringsNo authoritative reference available.falsefalse4false0stt_ImpairmentLossOnRestructuringOfLoanssttfalsedebitdurationImpairment Loss on Restructuring of Loansfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryImpairment Loss on Restructuring of LoansNo authoritative reference available.falsefalse5false0stt_LoansOrLeasesContractuallyPastDueDayssttfalsenadurationLoans or leases contractually past-due daysfalsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse9090falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:integerItemTypeintegerLoans or leases contractually past-due daysNo authoritative reference available.falsefalse6false0us-gaap_AllowanceForLoanAndLeaseLossesWriteOffsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1900000019000000falsefalsefalsefalsefalse2truefalsefalse30000003000000falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 20
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 7
-Subparagraph d
-Article 9
falsefalse7false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosureloansandleasesnarrativedetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalseUSDtruefalse{us-gaap_AccountsNotesLoansAndFinancingReceivablesByProductAndServiceTypeAxis} : Property Development - Acquired Credit-Impaired [Member]
1/1/2011 - 3/31/2011
USD ($)
$Duration_1_1_2011_To_3_31_2011_us-gaap_AccountsNotesLoansAndFinancingReceivablesByProductAndServiceTypeAxis_stt_PropertyDevelopmentAcquiredCreditImpairedMemberhttp://www.sec.gov/CIK0000093751duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseProperty Development - Acquired Credit-Impaired [Member]us-gaap_AccountsNotesLoansAndFinancingReceivablesByProductAndServiceTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_PropertyDevelopmentAcquiredCreditImpairedMemberus-gaap_AccountsNotesLoansAndFinancingReceivablesByProductAndServiceTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse8false0stt_ImpairedLoansRecordedPrincipalBalancesttfalsedebitinstantImpaired Loans Recorded Principal Balancefalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse4200000042000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryImpaired Loans Recorded Principal BalanceNo authoritative reference available.falsefalse9false0stt_OtherRealEstateOwnedsttfalsedebitinstantOther Real Estate Ownedfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse2200000022000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryOther Real Estate OwnedNo authoritative reference available.falsefalse10false0us-gaap_AllowanceForLoanAndLeaseLossesWriteOffsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1900000019000000falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 20
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 7
-Subparagraph d
-Article 9
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