Goodwill and Intangible Assets - Goodwill Attributable to Each Business Segments (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 13,978
Acquisitions	8
Other adjustments	(3)
Goodwill, Ending Balance	13,983
Credit Card
Goodwill [Roll Forward]
Goodwill, Beginning Balance	5,001
Acquisitions	1
Other adjustments	(3)
Goodwill, Ending Balance	4,999
Consumer Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,593
Acquisitions	7
Other adjustments	0
Goodwill, Ending Balance	4,600
Commercial Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,384
Acquisitions	0
Other adjustments	0
Goodwill, Ending Balance	$ 4,384