Business Segments - Schedule of Segment Results and Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 4,961	$ 4,760	$ 4,537	$ 4,576	$ 4,656	$ 4,497	$ 4,315	$ 4,350	$ 18,834	$ 17,818	$ 18,106
Non-interest income	1,233	1,140	1,135	1,071	1,157	1,142	1,153	1,020	4,579	4,472	4,278
Total net revenue									23,413	22,290	22,384
Provision for Loan, lease and Other losses	1,380	1,092	1,129	935	1,109	993	704	735	4,536	3,541	3,453
Amortization of intangibles									430	532	671
Other non-interest expense									12,586	11,682	11,754
Total non-interest expense	3,480	3,160	3,307	3,049	3,284	2,985	2,979	2,932	12,996	12,180	12,353
Income from continuing operations before income taxes	1,334	1,648	1,236	1,663	1,420	1,661	1,785	1,703	5,881	6,569	6,578
Income tax provision (benefit)	426	530	384	529	450	536	581	579	1,869	2,146	2,224
Income from continuing operations, net of tax	908	$ 1,118	$ 852	$ 1,134	970	$ 1,125	$ 1,204	$ 1,124	4,012	4,423	4,354
Loans held for investment	229,851				208,316				229,851	208,316	197,199
Total deposits	217,721				205,548				217,721	205,548	204,523
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income									11,161	10,310	10,967
Non-interest income									3,421	3,311	3,320
Total net revenue									14,582	13,621	14,287
Provision for Loan, lease and Other losses									3,417	2,750	2,824
Other non-interest expense									7,186	6,694	7,005
Total non-interest expense									7,502	7,063	7,439
Income from continuing operations before income taxes									3,663	3,808	4,024
Income tax provision (benefit)									1,309	1,329	1,409
Income from continuing operations, net of tax									2,354	2,479	2,615
Loans held for investment	96,125				85,876				96,125	85,876	81,305
Total deposits	0				0				0	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income									5,755	5,748	5,905
Non-interest income									710	684	749
Total net revenue									6,465	6,432	6,654
Provision for Loan, lease and Other losses									819	703	656
Other non-interest expense									3,947	3,761	3,607
Total non-interest expense									4,026	3,869	3,745
Income from continuing operations before income taxes									1,620	1,860	2,253
Income tax provision (benefit)									586	665	802
Income from continuing operations, net of tax									1,034	1,195	1,451
Loans held for investment	70,372				71,439				70,372	71,439	70,762
Total deposits	172,702				168,078				172,702	168,078	167,652
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income									1,865	1,751	1,674
Non-interest income									487	450	395
Total net revenue									2,352	2,201	2,069
Provision for Loan, lease and Other losses									302	93	(24)
Other non-interest expense									1,141	1,062	931
Total non-interest expense									1,156	1,083	958
Income from continuing operations before income taxes									894	1,025	1,135
Income tax provision (benefit)									324	366	404
Income from continuing operations, net of tax									570	659	731
Loans held for investment	63,266				50,890				63,266	50,890	45,011
Total deposits	34,257				31,954				34,257	31,954	30,567
Other
Segment Reporting Information [Line Items]
Net interest income									53	9	(440)
Non-interest income									(39)	27	(186)
Total net revenue									14	36	(626)
Provision for Loan, lease and Other losses									(2)	(5)	(3)
Other non-interest expense									312	165	211
Total non-interest expense									312	165	211
Income from continuing operations before income taxes									(296)	(124)	(834)
Income tax provision (benefit)									(350)	(214)	(391)
Income from continuing operations, net of tax									54	90	(443)
Loans held for investment	88				111				88	111	121
Total deposits	$ 10,762				$ 5,516				10,762	5,516	6,304
Purchased credit card relationship intangibles (“PCCR”)
Segment Reporting Information [Line Items]
Amortization of intangibles									316	369	434
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles									316	369	434
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									0	0	0
Purchased credit card relationship intangibles (“PCCR”) | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									0	0	0
Purchased credit card relationship intangibles (“PCCR”) | Other
Segment Reporting Information [Line Items]
Amortization of intangibles									0	0	0
Core deposit intangibles
Segment Reporting Information [Line Items]
Amortization of intangibles									94	129	165
Core deposit intangibles | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles									0	0	0
Core deposit intangibles | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									79	108	138
Core deposit intangibles | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									15	21	27
Core deposit intangibles | Other
Segment Reporting Information [Line Items]
Amortization of intangibles									0	0	0
PCCR and core deposits
Segment Reporting Information [Line Items]
Amortization of intangibles									410	498	599
PCCR and core deposits | Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Amortization of intangibles									316	369	434
PCCR and core deposits | Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									79	108	138
PCCR and core deposits | Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Amortization of intangibles									15	21	27
PCCR and core deposits | Other
Segment Reporting Information [Line Items]
Amortization of intangibles									$ 0	$ 0	$ 0