2.2.0.25falsefalse40901 - Disclosure - Variable Interest Entities (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$2falsefalseUSDfalsefalse1/1/2010 - 12/31/2010
USD ($)
$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$2true0stt_VariableInterestEntitiesAbstractsttfalsenadurationVariable Interest Entitiesfalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringVariable Interest Entitiesfalsefalse3false0stt_VariableInterestEntityFairValueOfCollateralizedAssetssttfalsedebitinstantVariable Interest Entity Fair Value Of Collateralized Assetsfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse27900000002790000000falsetruefalsefalsefalse2truefalsefalse28500000002850000000falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryVariable Interest Entity Fair Value Of Collateralized AssetsNo authoritative reference available.falsefalse4false0us-gaap_VariableInterestEntityCarryingAmountOfCollateralizedAssetsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse24500000002450000000falsefalsefalsefalsefalse2truefalsefalse25000000002500000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe carrying amount of the variable interest entity's assets consolidated into the statement of financial position. In general, a VIE is a corporation, partnership, trust, or any other legal structure used for business purposes that either (a) does not have equity investors with voting rights or (b) has equity investors that do not provide sufficient financial resources for the entity to support its activities. A VIE often holds financial assets, including loans or receivables, real estate or other property. A VIE may be essentially passive or it may engage in research and development or other activities on behalf of another company.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 26
-Subparagraph b
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4 and FIN46(R)-8
-Paragraph 9
-Subparagraph c(5), c(6)
Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 23
-Subparagraph a
Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4 and FIN46(R)-8
-Paragraph C5
-Subparagraph a
Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 23
-Subparagraph b
Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 24
-Subparagraph b
Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4 and FIN46(R)-8
-Paragraph C8
-Subparagraph b
falsefalse5false0stt_WeightedAverageLifeOfTrustssttfalsenainstantWeighted-average life of trusts.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse7.67.6falsefalsefalsefalsefalse2truefalsefalse7.77.7falsefalsefalsefalsefalseOtherxbrli:decimalItemTypedecimalWeighted-average life of trusts.No authoritative reference available.falsefalse6false0stt_TotalStandbyBondPurchaseAgreementCommitedToTrustssttfalsedebitinstantTotal standby bond purchase agreement committed to trusts.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse24900000002490000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTotal standby bond purchase agreement committed to trusts.No authoritative reference available.falsefalse7false0stt_AssetBackedSecuritiesFairValuesttfalsedebitinstantAsset Backed Securities Fair Valuefalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse60300000006030000000falsefalsefalsefalsefalse2truefalsefalse61100000006110000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAsset Backed Securities Fair ValueNo authoritative reference available.falsefalse8false0stt_PurchaseReceivableLoanssttfalsecreditdurationPurchase Receivable Loansfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse19800000001980000000falsefalsefalsefalsefalse2truefalsefalse22000000002200000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryPurchase Receivable LoansNo authoritative reference available.falsefalse9false0us-gaap_CommercialPaperus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse19200000001920000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.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 02
-Paragraph 19
-Subparagraph a(3)
-Article 5
Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 13
-Subparagraph 2
-Article 9
falsefalse10false0stt_AggregateNotionalValueOfTheseCDOssttfalsedebitinstantAggregate notional value of CDOs.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse10000000001000000000falsefalsefalsefalsefalse2truefalsefalse10000000001000000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAggregate notional value of CDOs.No authoritative reference available.falsefalse11false0stt_CarryingValueOfUnderlyingCollateralsttfalsedebitinstantCarrying value of the underlying collateral.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse308000000308000000falsetruefalsefalsefalse2truefalsefalse323000000323000000falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCarrying value of the underlying collateral.No authoritative reference available.falsefalse210Variable Interest Entities (Narrative) (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruetrue