Earnings Per Share - Components of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income attributable to U.S. Bancorp	$ 1,675	$ 1,473
Preferred dividends	(70)	(69)
Impact of preferred stock call		(10)
Earnings allocated to participating stock awards	(8)	(7)
Net income applicable to U.S. Bancorp common shareholders	$ 1,597	$ 1,387
Average common shares outstanding	1,652	1,694
Net effect of the exercise and assumed purchase of stock awards	5	7
Average diluted common shares outstanding	1,657	1,701
Earnings per common share	$ 0.97	$ 0.82
Diluted earnings per common share	$ 0.96	$ 0.82