Business Segments - Schedule of Segment Results and Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net interest income	$ 5,474	$ 5,056
Non-interest income	1,061	1,164
Total net revenue	6,535	6,220
Provision for loan, lease and other losses	1,992	1,527
Total non-interest expense	3,434	3,223
Income from continuing operations before income taxes	1,109	1,470
Income tax provision (benefit)	314	452
Income from continuing operations, net of tax	795	1,018
Loans held for investment	240,588	227,613	$ 245,586
Total deposits	241,182	221,779	$ 236,768
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income	3,346	3,033
Non-interest income	738	847
Total net revenue	4,084	3,880
Provision for loan, lease and other losses	1,717	1,071
Total non-interest expense	1,929	1,863
Income from continuing operations before income taxes	438	946
Income tax provision (benefit)	167	337
Income from continuing operations, net of tax	271	609
Loans held for investment	99,213	92,699
Total deposits	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	1,517	1,420
Non-interest income	195	191
Total net revenue	1,712	1,611
Provision for loan, lease and other losses	279	230
Total non-interest expense	1,042	990
Income from continuing operations before income taxes	391	391
Income tax provision (benefit)	143	142
Income from continuing operations, net of tax	248	249
Loans held for investment	73,982	70,591
Total deposits	188,216	177,803
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	566	537
Non-interest income	158	118
Total net revenue	724	655
Provision for loan, lease and other losses	(2)	228
Total non-interest expense	391	322
Income from continuing operations before income taxes	335	105
Income tax provision (benefit)	122	38
Income from continuing operations, net of tax	213	67
Loans held for investment	67,320	64,241
Total deposits	33,735	33,383
Other
Segment Reporting Information [Line Items]
Net interest income	45	66
Non-interest income	(30)	8
Total net revenue	15	74
Provision for loan, lease and other losses	(2)	(2)
Total non-interest expense	72	48
Income from continuing operations before income taxes	(55)	28
Income tax provision (benefit)	(118)	(65)
Income from continuing operations, net of tax	63	93
Loans held for investment	73	82
Total deposits	$ 19,231	$ 10,593