Earnings Per Share - Components of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income attributable to U.S. Bancorp	$ 1,815	$ 1,563	$ 5,240	$ 4,536
Preferred dividends	(76)	(71)	(210)	(204)
Impact of preferred stock redemption				(10)
Earnings allocated to participating stock awards	(7)	(7)	(23)	(20)
Net income applicable to U.S. Bancorp common shareholders	$ 1,732	$ 1,485	$ 5,007	$ 4,302
Average common shares outstanding	1,629	1,672	1,641	1,683
Net effect of the exercise and assumed purchase of stock awards	4	6	4	6
Average diluted common shares outstanding	1,633	1,678	1,645	1,689
Earnings per common share	$ 1.06	$ 0.89	$ 3.05	$ 2.56
Diluted earnings per common share	$ 1.06	$ 0.88	$ 3.04	$ 2.55