2.2.0.25truefalse41002 - Disclosure - Long-Term Debt (Long-Term Debt) (Details)truefalseIn Millions, unless otherwise specifiedfalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $Duration_1_1_2010_To_12_31_2010http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00Unit15Standardhttp://xbrl.us/us-types/2009-01-31sqftxbrlus0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2009 - 12/31/2009 USD ($) USD ($) / shares $Duration_1_1_2009_To_12_31_2009http://www.sec.gov/CIK0000093751duration2009-01-01T00:00:002009-12-31T00:00:00Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit14Divide http://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2false0us-gaap_LongTermDebtAndCapitalLeaseOblig ationsus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse716000000716falsetruefalsefalsefalse2truefalsefalse751000000751falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturit ies due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section H falsefalse3false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse85500000008550falsefalsefalsefalsefalse2truefalsefalse88380000008838falsefalsefalsefalsefalseMonetary< ElementDataType>xbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse4false0stt_IncreaseInCarryingValueOfLongTermDebtsttfalsedebitdurationIncrease In Carrying Value Of Long Term Debtfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefa lsefalse8100000081falsefalsefalsefalsefalse2truefalsefalse3100000031falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncrease In Carrying Value Of Long Term DebtNo authoritative reference available.falsefalse5false0us-gaap_DebtInstrumentInterestRateTermsus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse0081falsefalsefalsefalsefalse2falsefalsefalse0031falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDescription of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 falsefalse6false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Subordinated Notes Due To State Street Capital Trust IV In 2037 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201039http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFloating-Rate Subordinated Notes Due To State Street Capital Trust IV In 2037 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDueIn2037Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$4falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Subordinated Notes Due To State Street Capital Trust IV In 2037 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009101http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseFloating-Rate Subordinated Notes Due To State Street Capital Trust IV In 2037 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDueIn2037Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse7false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse800000000800falsefalsefalsefalsefalse2truefalsefalse800000000800falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes paya ble, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse8false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002037-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalseOtherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse9false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse5< /Id>falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 8.25% Fixed-To-Floating-Rate Subordinated Notes Due To State Street Capital Trust III In 2042 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_2010446http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse8.25% Fixed-To-Floating-Rate Subordinated Notes Due To State Street Capital Trust III In 2042 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_EightPointTwoFivePercentFixedToFloatingRateSubordinatedNotesDueIn2042Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$6falsefalseUSDtruefalse{us-ga ap_LongtermDebtTypeAxis} : 8.25% Fixed-To-Floating-Rate Subordinated Notes Due To State Street Capital Trust III In 2042 [Member] 12/31/2009 USD ($) $As_Of_12_31_200993http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse8.25% Fixed-To-Floating-Rate Subordinated Notes Due To State Street Capital Trust III In 2042 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_EightPointTwoFivePercentFixedToFloatingRateSubordinatedNotesDueIn2042Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse10false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse500000000500falsefalsefalsefalsefalse2truefalsefalse500000000500falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amou nt of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse11false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.08250.0825falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse12false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002042-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse13false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse7 falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 2.15% Notes Due 2012 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_20105243http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse2.15% Notes Due 2012 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_TwoPointOneFivePercentNotesDue2012Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$8falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 2.15% Notes Due 2012 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009106http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse2.15% Notes Due 2012 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_TwoPointOneFivePercentNotesDue2012Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse14false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse14990000001499falsefalsefalsefalsefalse2truefalsefalse14980000001498falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse15false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.02150.0215falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse16false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002012-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse17false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse9 falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 4.30% Notes Due 2014 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_20104423http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse4.30% Notes Due 2014 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FourPointThreeZeroPercentNotesDue2014Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$10falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 4.30% Notes Due 2014 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009102http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse4.30% Notes Due 2014 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FourPointThreeZeroPercentNotesDue2014Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217< MeasureValue>USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse18false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse500000000500falsefalsefalsefalsefalse2truefalsefalse500000000500falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond t he normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse19false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.0430.043falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse20false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1false falsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse< Id>11falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.375% Notes Due 2017 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_2010923http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse5.375% Notes Due 2017 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointThreeSevenFivePercentNotesDue2017Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$12falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.375% Notes Due 2017 [Member] 12/31/2009 USD ($) $As_Of_12_31_200994http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse5.375% Notes Due 2017 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointThreeSevenFivePercentNotesDue2017Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse21false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition avail able.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse450000000450falsefalsefalsefalsefalse2truefalsefalse450000000450falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or b eyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse22false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.053750.05375falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse23false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002017-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse24false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse1 3falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 7.65% Subordinated Notes Due 2010 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201041http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse7.65% Subordinated Notes Due 2010 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_SevenPointSixFivePercentSubordinatedNotesDue2010Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/i nstancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$14falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 7.65% Subordinated Notes Due 2010 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009104http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse7.65% Subordinated Notes Due 2010 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_SevenPointSixFivePercentSubordinatedNotesDue2010Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/ iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse25false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse305000000305falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initi al maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse26false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.07650.0765falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse27false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002014-05-30falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse28false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse1 5falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Notes Due 2012 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201036http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFloating-Rate Notes Due 2012 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateNotesDueTwoThousandTwelveMemberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$16falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Notes Due 2012 [Member] 12/31/2009 USD ($) $As_Of_12_31_200998http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseFloating-Rate Notes Due 2012 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateNotesDueTwoThousandTwelveMemberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse29false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse268000000268falsefalsefalsefalsefalse2truefalsefalse250000000250falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyo nd one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse30false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002012-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalseOtherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse31false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse1 7falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 7.35% Notes Due 2026 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_20104422http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse7.35% Notes Due 2026 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_SevenPointThreeFivePercentNotesDueTwoThousandTwentySixMemberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instan cepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$18falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 7.35% Notes Due 2026 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009105http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse7.35% Notes Due 2026 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_SevenPointThreeFivePercentNotesDueTwoThousandTwentySixMemberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217 USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse32false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo defini tion available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse150000000150falsefalsefalsefalse false2truefalsefalse150000000150falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse33false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.07350.0735falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse34false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002026-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse35false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse1 9falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating Rate Notes Due 2011 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201035http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFloating Rate Notes Due 2011 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateNotesDue2011Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$20falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating Rate Notes Due 2011 [Member] 12/31/2009 USD ($) $As_Of_12_31_200997http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseFloating Rate Notes Due 2011 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateNotesDue2011Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse36false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition av ailable.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse14500000001450falsefalsefalsefalsefalse 2truefalsefalse14500000001450falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one ye ar or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse37false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002011-03-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalseOtherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse38false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse2 1falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 1.85% Notes Due 2011 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201040http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse1.85% Notes Due 2011 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_OnePointEightFivePercentNotesDue2011Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$22falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 1.85% Notes Due 2011 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009103http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse1.85% Notes Due 2011 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_OnePointEightFivePercentNotesDue2011Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse39false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse10000000001000falsefalsefalsefalsefalse2truefalsefalse10000000001000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyon d the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse40false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.01850.0185falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse41false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002010-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse42false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse2 3falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.25% Subordinated Notes Due 2018 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_20104421http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse5.25% Subordinated Notes Due 2018 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointTwoFivePercentSubordinatedNotesDue2018Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/2003/ instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$24falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.25% Subordinated Notes Due 2018 [Member] 12/31/2009 USD ($) $As_Of_12_31_200996http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse5.25% Subordinated Notes Due 2018 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointTwoFivePercentSubordinatedNotesDue2018Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/is o4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse43false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse439000000439falsefalsefalsefa lsefalse2truefalsefalse430000000430falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which ha d initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse44false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.05250.0525falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse45false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002018-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse46false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse2 5falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.30% Subordinated Notes Due 2016 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_20104420http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalse5.30% Subordinated Notes Due 2016 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointThreeZeroPercentSubordinatedNotesDue2016Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit13Standardhttp://www.xbrl.org/200 3/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$26falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : 5.30% Subordinated Notes Due 2016 [Member] 12/31/2009 USD ($) $As_Of_12_31_200995http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalse5.30% Subordinated Notes Due 2016 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FivePointThreeZeroPercentSubordinatedNotesDue2016Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/ iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse47false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse423000000423falsefalsefalse falsefalse2truefalsefalse399000000399falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse48false0us-gaap_SubordinatedBorrowingInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.0530.053falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureStated interest rate of the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse49false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002016-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalse< Unit>Otherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse50false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse2 7falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating Rate Subordinated Notes Due 2015 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201037http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFloating Rate Subordinated Notes Due 2015 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDue2015Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso42 17USDiso42170$28falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating Rate Subordinated Notes Due 2015 [Member] 12/31/2009 USD ($) $As_Of_12_31_200999http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseFloating Rate Subordinated Notes Due 2015 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDue2015Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso42 17USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse51false0us-gaap_LongTermDebtus-gaaptruecreditin stantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse200000000200falsefalsefalsefalsefalse2truefalsefalse200000000200falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of d ebt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse52false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002015-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalseOtherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse53false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse2 9falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Subordinated Notes Due To State Street Capital Trust I In 2028 [Member] 1/1/2010 - 12/31/2010 Duration_1_1_2010_To_12_31_201038http://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFloating-Rate Subordinated Notes Due To State Street Capital Trust I In 2028 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDueIn2028Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170$30falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Floating-Rate Subordinated Notes Due To State Street Capital Trust I In 2028 [Member] 12/31/2009 USD ($) $As_Of_12_31_2009100http://www.sec.gov/CIK0000093751instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseFloating-Rate Subordinated Notes Due To State Street Capital Trust I In 2028 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldistt_FloatingRateSubordinatedNotesDueIn2028Memberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse54false0us-gaap_LongTermDebtus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse155000000155falsefalsefalsefalsefalse2truefalsefalse155000000155falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncluding current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payabl e, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 falsefalse55false0us-gaap_SubordinatedBorrowingDueDateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002028-01-01falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruefalsefalseOtherxbrli:dateItemTypedateDate payments are due on the subordinated debt.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 08 -IssueDate 2006-05-01 falsefalse56false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosurelongtermdebtlongtermdebtdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3 1falsefalseUSDtruefalse{us-gaap_LongtermDebtTypeAxis} : Fair Value Hedges [Member] 1/1/2009 - 12/31/2009 USD ($) $Duration_1_1_2009_To_12_31_20097247http://www.sec.gov/CIK0000093751duration2009-01-01T00:00:002009-12-31T00:00:00falsefalseFair Value Hedges [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FairValueHedgingMemberus-gaap_LongtermDebtTypeAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse57false0stt_IncreaseInCarryingValueOfLongTermDebtsttfalsedebitdurationIncrea se In Carrying Value Of Long Term Debtfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse3100000031falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncrease In Carrying Value Of Long Term DebtNo authoritative reference available.falsefalse256Long-Term Debt (Long-Term Debt) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruetrue