Derivative Instruments - Customer-Related Derivative Positions of Company (Detail) - Customer-Related Positions [Member] - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Value, Assets	$ 227,658	$ 184,339
Fair Value, Assets	2,667	1,855
Notional Value, Liabilities	209,169	188,667
Fair Value, Liabilities	1,471	1,672
Interest Rate Contracts [Member] \| Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	105,152	42,054
Fair Value, Assets	$ 1,926	$ 754
Derivative Asset Average Remaining Maturity Period	5 years 3 months 21 days	6 years 8 months 23 days
Notional Value, Liabilities	$ 21,853	$ 60,731
Fair Value, Liabilities	$ 47	$ 456
Derivative Liability Average Remaining Maturity Period	3 years 1 month 28 days	4 years 3 months 25 days
Interest Rate Contracts [Member] \| Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 22,375	$ 60,970
Fair Value, Assets	$ 47	$ 288
Derivative Asset Average Remaining Maturity Period	2 years 8 months 26 days	3 years 10 months 24 days
Notional Value, Liabilities	$ 100,241	$ 40,499
Fair Value, Liabilities	$ 753	$ 420
Derivative Liability Average Remaining Maturity Period	5 years 2 months 26 days	6 years 6 months 25 days
Interest Rate Contracts [Member] \| Other Derivatives [Member]
Derivative [Line Items]
Notional Value, Assets	$ 8,117	$ 5,777
Fair Value, Assets	$ 2	$ 2
Derivative Asset Average Remaining Maturity Period	3 years 3 months 18 days	3 years 9 months 7 days
Notional Value, Liabilities	$ 5,789	$ 6,496
Fair Value, Liabilities	$ 3	$ 2
Derivative Liability Average Remaining Maturity Period	3 years 29 days	2 years 8 months 19 days
Interest Rate Contracts [Member] \| Options [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 48,316	$ 41,711
Fair Value, Assets	$ 38	$ 51
Derivative Asset Average Remaining Maturity Period	1 year 4 months 6 days	1 year 6 months 14 days
Notional Value, Liabilities	$ 2,745	$ 1,940
Fair Value, Liabilities	$ 75	$ 30
Derivative Liability Average Remaining Maturity Period	6 years 5 months 23 days	1 year 11 months 23 days
Interest Rate Contracts [Member] \| Options [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Assets	$ 10,018	$ 2,060
Fair Value, Assets	$ 77	$ 32
Derivative Asset Average Remaining Maturity Period	1 year 10 months 24 days	2 years 25 days
Notional Value, Liabilities	$ 38,506	$ 39,538
Fair Value, Liabilities	$ 33	$ 51
Derivative Liability Average Remaining Maturity Period	1 year 5 months 19 days	1 year 5 months 8 days
Interest Rate Contracts [Member] \| Futures [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 92	$ 460
Derivative Asset Average Remaining Maturity Period	11 months 19 days	1 year 6 months 29 days
Interest Rate Contracts [Member] \| Futures [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Assets	$ 917
Derivative Asset Average Remaining Maturity Period	1 year 10 months 2 days
Notional Value, Liabilities	$ 4,363	$ 6,190
Fair Value, Liabilities	$ 3	$ 1
Derivative Liability Average Remaining Maturity Period	11 months 1 day	7 months 2 days
Foreign Exchange Rate Contracts [Member] \| Forwards, Spots and Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 28,464	$ 26,210
Fair Value, Assets	$ 552	$ 681
Derivative Asset Average Remaining Maturity Period	1 year 1 month 20 days	10 months 28 days
Notional Value, Liabilities	$ 27,241	$ 25,571
Fair Value, Liabilities	$ 528	$ 663
Derivative Liability Average Remaining Maturity Period	1 year 3 months 21 days	10 months 17 days
Foreign Exchange Option [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 1,680	$ 2,779
Fair Value, Assets	$ 24	$ 47
Derivative Asset Average Remaining Maturity Period	9 months	9 months
Foreign Exchange Option [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Liabilities	$ 1,680	$ 2,779
Fair Value, Liabilities	$ 24	$ 47
Derivative Liability Average Remaining Maturity Period	9 months	9 months
Credit Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	$ 2,527	$ 2,318
Fair Value, Assets	$ 1
Derivative Asset Average Remaining Maturity Period	3 years 1 month 24 days	3 years 6 months
Notional Value, Liabilities	$ 6,751	$ 4,923
Fair Value, Liabilities	$ 5	$ 2
Derivative Liability Average Remaining Maturity Period	4 years 11 months 1 day	4 years 14 days

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeAssetNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

+ References

+ Details

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

- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeLiabilityNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
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_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative asset average remaining maturity period.

+ References

No definition available.

+ Details

Name:	usb_DerivativeAssetAverageRemainingMaturity
Namespace Prefix:	usb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative liability average remaining maturity period.

+ References

No definition available.

+ Details

Name:	usb_DerivativeLiabilityAverageRemainingMaturity
Namespace Prefix:	usb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NotDesignatedAsHedgingInstrumentTradingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=usb_ReceiveFixedPayFloatingSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=usb_PayFixedReceiveFloatingSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_OtherContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_OptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FutureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=usb_ForwardsSpotsAndSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CreditRiskContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: