Restrictions on Cash and Due from Banks - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Cash and Cash Equivalents [Abstract]
Minimum average reserve balances to be maintain at bank subsidiaries	$ 2.0	$ 1.8
Balances held at the federal reserve	$ 4.4usb_BalancesHeldAtFederalReserve	$ 1.9usb_BalancesHeldAtFederalReserve

Minimum Average Reserve Balances Required By Federal Reserve

No definition available.

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