Components of Earnings per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income attributable to U.S. Bancorp	$ 1,474	$ 1,273	$ 4,227	$ 3,522
Preferred dividends	(64)	(30)	(174)	(99)
Earnings allocated to participating stock awards	(6)	(6)	(19)	(16)
Net income applicable to U.S. Bancorp common shareholders	$ 1,404	$ 1,237	$ 4,034	$ 3,407
Average common shares outstanding	1,886	1,915	1,892	1,918
Net effect of the exercise and assumed purchase of stock awards and conversion of outstanding convertible notes	11	7	9	8
Average diluted common shares outstanding	1,897	1,922	1,901	1,926
Earnings per common share	$ 0.74	$ 0.65	$ 2.13	$ 1.78
Diluted earnings per common share	$ 0.74	$ 0.64	$ 2.12	$ 1.77