Business Segments - Schedule of Segment Results and Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 4,760	$ 4,497	$ 13,873	$ 13,162
Non-interest income	1,140	1,142	3,346	3,315
Total net revenue	5,900	5,639	17,219	16,477
Provision for Loan, lease and Other losses	1,092	993	3,156	2,432
Amortization of intangibles	106	130	327	409
Other non-interest expense	3,060	2,864	9,201	8,514
Total non-interest expense	3,160	2,985	9,516	8,896
Income from continuing operations before income taxes	1,648	1,661	4,547	5,149
Income tax provision (benefit)	530	536	1,443	1,696
Income from continuing operations, net of tax	1,118	1,125	3,104	3,453
Loans held for investment	213,329	201,592	213,329	201,592	$ 208,316
Total deposits	212,903	204,264	212,903	204,264	$ 205,548
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income	2,866	2,627	8,165	7,613
Non-interest income	858	846	2,519	2,470
Total net revenue	3,724	3,473	10,684	10,083
Provision for Loan, lease and Other losses	831	787	2,395	1,894
Other non-interest expense	1,770	1,640	5,239	4,893
Total non-interest expense	1,848	1,730	5,481	5,175
Income from continuing operations before income taxes	1,045	956	2,808	3,014
Income tax provision (benefit)	375	332	1,007	1,054
Income from continuing operations, net of tax	670	624	1,801	1,960
Loans held for investment	90,135	80,631	90,135	80,631
Total deposits	0	0	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	1,443	1,425	4,321	4,289
Non-interest income	174	179	528	499
Total net revenue	1,617	1,604	4,849	4,788
Provision for Loan, lease and Other losses	188	198	579	481
Other non-interest expense	982	930	2,907	2,740
Total non-interest expense	1,001	956	2,969	2,824
Income from continuing operations before income taxes	428	450	1,301	1,483
Income tax provision (benefit)	155	161	471	530
Income from continuing operations, net of tax	273	289	830	953
Loans held for investment	70,990	71,061	70,990	71,061
Total deposits	170,866	167,624	170,866	167,624
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	454	439	1,381	1,296
Non-interest income	108	122	345	318
Total net revenue	562	561	1,726	1,614
Provision for Loan, lease and Other losses	75	9	184	61
Other non-interest expense	269	263	803	774
Total non-interest expense	272	268	814	790
Income from continuing operations before income taxes	215	284	728	763
Income tax provision (benefit)	78	102	264	273
Income from continuing operations, net of tax	137	182	464	490
Loans held for investment	52,112	49,788	52,112	49,788
Total deposits	32,751	31,918	32,751	31,918
Other
Segment Reporting Information [Line Items]
Net interest income	(3)	6	6	(36)
Non-interest income	0	(5)	(46)	28
Total net revenue	(3)	1	(40)	(8)
Provision for Loan, lease and Other losses	(2)	(1)	(2)	(4)
Other non-interest expense	39	31	252	107
Total non-interest expense	39	31	252	107
Income from continuing operations before income taxes	(40)	(29)	(290)	(111)
Income tax provision (benefit)	(78)	(59)	(299)	(161)
Income from continuing operations, net of tax	38	30	9	50
Loans held for investment	92	112	92	112
Total deposits	9,286	4,722	9,286	4,722
Purchased credit card relationship intangibles (“PCCR”)
Segment Reporting Information [Line Items]
Amortization of intangibles	78	90	242	282
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	78	90	242	282
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
Purchased credit card relationship intangibles (“PCCR”) | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
Core deposit intangibles
Segment Reporting Information [Line Items]
Amortization of intangibles	22	31	73	100
Core deposit intangibles | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
Core deposit intangibles | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	19	26	62	84
Core deposit intangibles | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	3	5	11	16
Core deposit intangibles | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
PCCR and core deposits
Segment Reporting Information [Line Items]
Amortization of intangibles	100	121	315	382
PCCR and core deposits | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	78	90	242	282
PCCR and core deposits | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	19	26	62	84
PCCR and core deposits | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	3	5	11	16
PCCR and core deposits | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 0	$ 0	$ 0	$ 0