Goodwill and Intangible Assets - Goodwill Attributable to Each Business Segments (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 14,544
Other adjustments	2
Goodwill, ending balance	14,546
Credit Card
Goodwill [Roll Forward]
Goodwill, beginning balance	5,060
Other adjustments	2
Goodwill, ending balance	5,062
Consumer Banking
Goodwill [Roll Forward]
Goodwill, beginning balance	4,600
Other adjustments	0
Goodwill, ending balance	4,600
Commercial Banking
Goodwill [Roll Forward]
Goodwill, beginning balance	4,884
Other adjustments	0
Goodwill, ending balance	$ 4,884