Restrictions on Cash and Due from Banks - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Minimum Average Reserve Balances Required By Banking Regulators	$ 73	$ 3,200
Balances held at the central banks and other financial institutions	$ 55,400	$ 16,200

Balances held at central banks and other financial institutions in order to meet requirements and for other purposes.

No definition available.

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