Business Segments - Schedule of Segment Results and Reconciliation (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 4,497	$ 4,560	$ 13,162	$ 13,683
Non-interest income	1,142	1,091	3,315	3,157
Total net revenue	5,639	5,651	16,477	16,840
Provision (benefit) for credit losses	993	849	2,432	2,496
Amortization of intangibles	130	161	409	505
Other non-interest expense	2,864	2,963	8,514	8,659
Total non-interest expense	2,985	3,109	8,896	9,118
Income from continuing operations before income taxes	1,661	1,693	5,149	5,226
Income tax provision (benefit)	536	575	1,696	1,747
Income from continuing operations, net of tax	1,125	1,118	3,453	3,479
Loans held-for-investment	201,592	191,814	201,592	191,814	197,199
Period-end total deposits	204,264	206,834	204,264	206,834	204,523
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income	2,627	2,757	7,613	8,391
Non-interest income	846	834	2,470	2,487
Total net revenue	3,473	3,591	10,083	10,878
Provision (benefit) for credit losses	787	617	1,894	2,073
Other non-interest expense	1,640	1,798	4,893	5,239
Total non-interest expense	1,730	1,904	5,175	5,571
Income from continuing operations before income taxes	956	1,070	3,014	3,234
Income tax provision (benefit)	332	376	1,054	1,135
Income from continuing operations, net of tax	624	694	1,960	2,099
Loans held-for-investment	80,631	77,967	80,631	77,967
Period-end total deposits	0	0	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	1,425	1,481	4,289	4,437
Non-interest income	179	184	499	554
Total net revenue	1,604	1,665	4,788	4,991
Provision (benefit) for credit losses	198	202	481	444
Other non-interest expense	930	893	2,740	2,621
Total non-interest expense	956	927	2,824	2,727
Income from continuing operations before income taxes	450	536	1,483	1,820
Income tax provision (benefit)	161	191	530	648
Income from continuing operations, net of tax	289	345	953	1,172
Loans held-for-investment	71,061	71,285	71,061	71,285
Period-end total deposits	167,624	168,437	167,624	168,437
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	439	424	1,296	1,227
Non-interest income	122	87	318	264
Total net revenue	561	511	1,614	1,491
Provision (benefit) for credit losses	9	31	61	(18)
Other non-interest expense	263	222	774	656
Total non-interest expense	268	228	790	677
Income from continuing operations before income taxes	284	252	763	832
Income tax provision (benefit)	102	90	273	296
Income from continuing operations, net of tax	182	162	490	536
Loans held-for-investment	49,788	42,399	49,788	42,399
Period-end total deposits	31,918	30,592	31,918	30,592
Other
Segment Reporting Information [Line Items]
Net interest income	6	(102)	(36)	(372)
Non-interest income	(5)	(14)	28	(148)
Total net revenue	1	(116)	(8)	(520)
Provision (benefit) for credit losses	(1)	(1)	(4)	(3)
Other non-interest expense	31	50	107	143
Total non-interest expense	31	50	107	143
Income from continuing operations before income taxes	(29)	(165)	(111)	(660)
Income tax provision (benefit)	(59)	(82)	(161)	(332)
Income from continuing operations, net of tax	30	(83)	50	(328)
Loans held-for-investment	112	163	112	163
Period-end total deposits	4,722	7,805	4,722	7,805
Purchased credit card relationship intangibles (“PCCR”)
Segment Reporting Information [Line Items]
Amortization of intangibles	90	106	282	332
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	90	106	282	332
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	31	40	100	127
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	26	34	84	106
Core deposit intangibles | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	5	6	16	21
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	121	146	382	459
PCCR and core deposits | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles	90	106	282	332
PCCR and core deposits | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	26	34	84	106
PCCR and core deposits | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles	5	6	16	21
PCCR and core deposits | Other
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 0	$ 0	$ 0	$ 0