Guarantees and Contingent Liabilities - Summary of Other Guarantees and Contingent Liabilities (Detail) $ in Millions	Sep. 30, 2020 USD ($)
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Carrying Amount	$ 69
Maximum Potential Future Payments	9,838
Third Party Borrowing Arrangements [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	2
Securities Lending Indemnifications [Member]
Guarantor Obligations [Line Items]
Collateral Held	5,790
Maximum Potential Future Payments	5,659
Asset Sales [Member]
Guarantor Obligations [Line Items]
Carrying Amount	75
Maximum Potential Future Payments	5,148
Merchant Processing [Member]
Guarantor Obligations [Line Items]
Collateral Held	668
Carrying Amount	203
Maximum Potential Future Payments	88,546
Tender Option Bond Program Guarantee [Member]
Guarantor Obligations [Line Items]
Collateral Held	2,796
Maximum Potential Future Payments	2,445
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Carrying Amount	74
Maximum Potential Future Payments	$ 1,450

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Guarantee obligations collateral held.

+ References

No definition available.

+ Details

Name:	usb_GuaranteeObligationsCollateralHeld
Namespace Prefix:	usb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=usb_ThirdPartyBorrowingArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_IndemnificationGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=usb_AssetsSalesArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=usb_MerchantProcessingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=usb_TenderOptionBondProgramGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_GuaranteeTypeOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: