Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Components of earnings per share
Net income attributable to U.S. Bancorp	$ 1,338	$ 1,046
Preferred stock dividends	(46)	(39)
Earnings allocated to participating stock awards	(7)	(4)
Net income applicable to U.S. Bancorp common shareholders	$ 1,285	$ 1,003
Average common shares outstanding	1,901	1,918
Net effect of the exercise and assumed purchase of stock awards and conversion of outstanding convertible notes	9	10
Average diluted common shares outstanding	1,910	1,928
Earnings per common share	$ 0.68	$ 0.52
Diluted earnings per common share	$ 0.67	$ 0.52
Stock Option [Member]
Earnings per Share (Textual) [Abstract]
Options outstanding of common shares	45	55