2.2.0.25truefalse40502 - Disclosure - Goodwill and Other Intangible Assets (Changes in the Carrying Amount of Other Intangible Assets) (Details)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2011 - 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/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse25930000002593falsetruefalsefalsefalse2truefalsefalse18100000001810falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse3false0stt_AcquisitionOfAssetManagementBusinessBusinessIntangiblesttfalsedebitdurationThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse2700000027falsefalsefalsefalsefalse2falsefalsefalse00 falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.No authoritative reference available.falsefalse4false0us-gaap_AmortizationOfIntangibleAssetsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-49000000-49falsefalsefalsefalsefalse2truefalsefalse-34000000-34falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph a(2) falsefalse5false0us-gaap_IndefiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustmentsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse7100000071falsefalsefalsefalsefalse2truefalsefalse-16000000-16falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReflects net changes to the recorded value of indefinite-lived intangible assets for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of indefinite-lived intangible assets to fair value.No authoritative reference available.falsefalse6false0stt_OtherIntangibleAssetsNetsttfalsedebitinstantThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse20000002falsefalsefalsefalsefalse2truefalsefalse80000008falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are not separately presented on the statement of financial position.No authoritative reference available.falsefalse7false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse26440000002644falsefalsefalsefalsefalse2truefalsefalse17680000001768falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse8false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosuregoodwillandotherintangibleassetschangesincarryingamountofotherintangibleassetsdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalseUSDtruefalse{us-gaap_StatementBusinessSegmentsAxis} : Investment Servicing [Member] 1/1/2011 - 3/31/2011 USD ($) $Duration_1_1_2011_To_3_31_2011_us-gaap_StatementBusinessSegmentsAxis_stt_InvestmentServicingMemberhttp://www.sec.gov/CIK0000093751duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseInvestment Servicing [Member]us-gaap_StatementBusinessSegmentsAxisxbrldihttp://xbrl.org/2006/xbrldistt_InvestmentServicingMemberus-gaap_StatementBusinessSegmentsAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$4falsefalseUSDtruefalse{us-gaap_StatementBusinessSegmentsAxis} : Investment Servicing [Member] 1/1/2010 - 3/31/2010 USD ($) $Duration_1_1_2010_To_3_31_2010_us-gaap_StatementBusinessSegmentsAxis_stt_InvestmentServicingMemberhttp://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-03-31T00:00:00falsefalseInvestment Servicing [Member]us-gaap_StatementBusinessSegmentsAxisxbrldihttp://xbrl.org/2006/xbrldistt_InvestmentServicingMemberus-gaap_StatementBusinessSegmentsAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse9false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse25590000002559falsefalsefalsefalsefalse2truefalsefalse17600000001760falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse10false0stt_AcquisitionOfAssetManagementBusinessBusinessIntangiblesttfalsedebitdurationThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00 falsefalsefalsefalsefalse2falsefalsefalse00 falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.No authoritative reference available.falsefalse11false0us-gaap_AmortizationOfIntangibleAssetsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-46000000-46falsefalsefalsefalsefalse2truefalsefalse-32000000-32falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph a(2) falsefalse12false0us-gaap_IndefiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustmentsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse7000000070falsefalsefalsefalsefalse2truefalsefalse-14000000-14falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReflects net changes to the recorded value of indefinite-lived intangible assets for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of indefinite-lived intangible assets to fair value.No authoritative reference available.falsefalse13false0stt_OtherIntangibleAssetsNetsttfalsedebitinstantThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00 falsefalsefalsefalsefalse2falsefalsefalse00 falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are not separately presented on the statement of financial position.No authoritative reference available.falsefalse14false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse25830000002583falsefalsefalsefalsefalse2truefalsefalse17140000001714falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse15false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.statestreet.com/taxonomy/role/disclosuregoodwillandotherintangibleassetschangesincarryingamountofotherintangibleassetsdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse5falsefalseUSDtruefalse{us-gaap_StatementBusinessSegmentsAxis} : Investment Management [Member] 1/1/2011 - 3/31/2011 USD ($) $Duration_1_1_2011_To_3_31_2011_us-gaap_StatementBusinessSegmentsAxis_stt_InvestmentManagementMemberhttp://www.sec.gov/CIK0000093751duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseInvestment Management [Member]us-gaap_StatementBusinessSegmentsAxisxbrldihttp://xbrl.org/2006/xbrldistt_InvestmentManagementMemberus-gaap_StatementBusinessSegmentsAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$6falsefalseUSDtruefalse{us-gaap_StatementBusinessSegmentsAxis} : Investment Management [Member] 1/1/2010 - 3/31/2010 USD ($) $Duration_1_1_2010_To_3_31_2010_us-gaap_StatementBusinessSegmentsAxis_stt_InvestmentManagementMemberhttp://www.sec.gov/CIK0000093751duration2010-01-01T00:00:002010-03-31T00:00:00falsefalseInvestment Management [Member]us-gaap_StatementBusinessSegmentsAxisxbrldihttp://xbrl.org/2006/xbrldistt_InvestmentManagementMemberus-gaap_StatementBusinessSegmentsAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse16false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse3400000034falsefalsefalsefalsefalse2truefalsefalse5000000050falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse17false0stt_AcquisitionOfAssetManagementBusinessBusinessIntangiblesttfalsedebitdurationThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse2700000027falsefalsefalsefalsefalse2falsefalsefalse00 falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cost of asset management business allocated to an identifiable intangible asset, excluding goodwill.No authoritative reference available.falsefalse18false0us-gaap_AmortizationOfIntangibleAssetsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-3000000-3falsefalsefalsefalsefalse2truefalsefalse-2000000-2falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph a(2) falsefalse19false0us-gaap_IndefiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustmentsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse10000001falsefalsefalsefalsefalse2truefalsefalse-2000000-2falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReflects net changes to the recorded value of indefinite-lived intangible assets for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of indefinite-lived intangible assets to fair value.No authoritative reference available.falsefalse20false0stt_OtherIntangibleAssetsNetsttfalsedebitinstantThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse20000002falsefalsefalsefalsefalse2truefalsefalse80000008falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are not separately presented on the statement of financial position.No authoritative reference available.falsefalse21false0us-gaap_IntangibleAssetsNetExcludingGoodwillus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse6100000061falsetruefalsefalsefalse2truefalsefalse5400000054falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 42, 45 falsefalse220Goodwill and Other Intangible Assets (Changes in the Carrying Amount of Other Intangible Assets) (Details) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue