Goodwill and Intangible Assets - Goodwill Attributable to Each Business Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 14,533	$ 14,519	$ 14,480
Goodwill, Acquired During Period	33	6	54
Goodwill, Written off Related to Sale of Business Unit	(17)
Other adjustments	(5)	8	(15)
Goodwill, Ending Balance	14,544	14,533	14,519
Credit Card
Goodwill [Roll Forward]
Goodwill, Beginning Balance	5,032	5,018	4,997
Goodwill, Acquired During Period	33	6	36
Goodwill, Written off Related to Sale of Business Unit	0
Other adjustments	(5)	8	(15)
Goodwill, Ending Balance	5,060	5,032	5,018
Consumer Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,600	4,600	4,600
Goodwill, Acquired During Period	0	0	0
Goodwill, Written off Related to Sale of Business Unit	0
Other adjustments	0	0	0
Goodwill, Ending Balance	4,600	4,600	4,600
Commercial Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,901	4,901	4,883
Goodwill, Acquired During Period	0	0	18
Goodwill, Written off Related to Sale of Business Unit	(17)
Other adjustments	0	0	0
Goodwill, Ending Balance	$ 4,884	$ 4,901	$ 4,901