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Accounting for Transfers and Servicing of Financial Assets and Variable Interest Entities - Summary of Investments in Community Development and Tax-advantaged VIEs (Detail) (Community Development and Tax Advantaged Investments [Member], USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Community Development and Tax Advantaged Investments [Member]
    
Variable Interest Entity [Line Items]    
Investment carrying amount $ 4,659us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember		 $ 4,259us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember
Unfunded capital and other commitments 2,034us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountLiabilities
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember		 1,743us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountLiabilities
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember
Maximum exposure to loss $ 8,478us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember		 $ 8,393us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= usb_CommunityDevelopmentAndTaxAdvantagedInvestmentsMember