Business Segments - Schedule of Segment Results and Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net interest income	$ 5,056	$ 4,576
Non-interest income	1,164	1,071
Total net revenue	6,220	5,647
Provision for Loan, lease and Other losses	1,527	935
Amortization of intangibles	101	110
Other non-interest expense	3,135	2,939
Total non-interest expense	3,223	3,049
Income from continuing operations before income taxes	1,470	1,663
Income tax provision (benefit)	452	529
Income from continuing operations, net of tax	1,018	1,134
Loans held for investment	227,613	203,978	$ 229,851
Total deposits	221,779	210,440	$ 217,721
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income	3,033	2,666
Non-interest income	847	816
Total net revenue	3,880	3,482
Provision for Loan, lease and Other losses	1,071	669
Other non-interest expense	1,793	1,692
Total non-interest expense	1,863	1,776
Income from continuing operations before income taxes	946	1,037
Income tax provision (benefit)	337	369
Income from continuing operations, net of tax	609	668
Loans held for investment	92,699	81,754
Total deposits	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	1,420	1,434
Non-interest income	191	158
Total net revenue	1,611	1,592
Provision for Loan, lease and Other losses	230	206
Other non-interest expense	975	948
Total non-interest expense	990	970
Income from continuing operations before income taxes	391	416
Income tax provision (benefit)	142	150
Income from continuing operations, net of tax	249	266
Loans held for investment	70,591	71,379
Total deposits	177,803	172,502
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	537	461
Non-interest income	118	114
Total net revenue	655	575
Provision for Loan, lease and Other losses	228	60
Other non-interest expense	319	268
Total non-interest expense	322	272
Income from continuing operations before income taxes	105	243
Income tax provision (benefit)	38	88
Income from continuing operations, net of tax	67	155
Loans held for investment	64,241	50,741
Total deposits	33,383	32,575
Other
Segment Reporting Information [Line Items]
Net interest income	66	15
Non-interest income	8	(17)
Total net revenue	74	(2)
Provision for Loan, lease and Other losses	(2)	0
Other non-interest expense	48	31
Total non-interest expense	48	31
Income from continuing operations before income taxes	28	(33)
Income tax provision (benefit)	(65)	(78)
Income from continuing operations, net of tax	93	45
Loans held for investment	82	104
Total deposits	10,593	5,363
Purchased credit card relationship intangibles (“PCCR”)
Segment Reporting Information [Line Items]
Amortization of intangibles	70	84
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	70	84
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0
Purchased credit card relationship intangibles (“PCCR”) | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0
Core deposit intangibles
Segment Reporting Information [Line Items]
Amortization of intangibles	18	26
Core deposit intangibles | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0
Core deposit intangibles | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	15	22
Core deposit intangibles | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	3	4
Core deposit intangibles | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0
PCCR and core deposits
Segment Reporting Information [Line Items]
Amortization of intangibles	88	110
PCCR and core deposits | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	70	84
PCCR and core deposits | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	15	22
PCCR and core deposits | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	3	4
PCCR and core deposits | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 0	$ 0