Business Segments - Schedule of Segment Results and Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 5,447	$ 5,277	$ 5,093	$ 5,056	$ 4,961	$ 4,760	$ 4,537	$ 4,576	$ 20,873	$ 18,834	$ 17,818
Non-interest income	1,119	1,184	1,161	1,164	1,233	1,140	1,135	1,071	4,628	4,579	4,472
Total net revenue									25,501	23,413	22,290
Provision for loan, lease and other losses	1,752	1,588	1,592	1,527	1,380	1,092	1,129	935	6,459	4,536	3,541
Total non-interest expense	3,679	3,361	3,295	3,223	3,480	3,160	3,307	3,049	13,558	12,996	12,180
Income from continuing operations before income taxes	1,135	1,512	1,367	1,470	1,334	1,648	1,236	1,663	5,484	5,881	6,569
Income tax provision (benefit)	342	496	424	452	426	530	384	529	1,714	1,869	2,146
Income from continuing operations, net of tax	793	$ 1,016	$ 943	$ 1,018	908	$ 1,118	$ 852	$ 1,134	3,770	4,012	4,423
Loans held for investment	245,586				229,851				245,586	229,851	208,316
Total deposits	236,768				217,721				$ 236,768	$ 217,721	$ 205,548
Effective income tax rate									35.00%	35.00%	35.00%
Operating Segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income									$ 12,635	$ 11,161	$ 10,310
Non-interest income									3,380	3,421	3,311
Total net revenue									16,015	14,582	13,621
Provision for loan, lease and other losses									4,926	3,417	2,750
Total non-interest expense									7,703	7,502	7,063
Income from continuing operations before income taxes									3,386	3,663	3,808
Income tax provision (benefit)									1,226	1,309	1,329
Income from continuing operations, net of tax									2,160	2,354	2,479
Loans held for investment	105,552				96,125				105,552	96,125	85,876
Total deposits	0				0				0	0	0
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income									5,829	5,755	5,748
Non-interest income									733	710	684
Total net revenue									6,562	6,465	6,432
Provision for loan, lease and other losses									1,055	819	703
Total non-interest expense									4,139	4,026	3,869
Income from continuing operations before income taxes									1,368	1,620	1,860
Income tax provision (benefit)									498	586	665
Income from continuing operations, net of tax									870	1,034	1,195
Loans held for investment	73,054				70,372				73,054	70,372	71,439
Total deposits	181,917				172,702				181,917	172,702	168,078
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income									2,216	1,865	1,751
Non-interest income									578	487	450
Total net revenue									2,794	2,352	2,201
Provision for loan, lease and other losses									483	302	93
Total non-interest expense									1,407	1,156	1,083
Income from continuing operations before income taxes									904	894	1,025
Income tax provision (benefit)									329	324	366
Income from continuing operations, net of tax									575	570	659
Loans held for investment	66,916				63,266				66,916	63,266	50,890
Total deposits	33,866				34,257				33,866	34,257	31,954
Other
Segment Reporting Information [Line Items]
Net interest income									193	53	9
Non-interest income									(63)	(39)	27
Total net revenue									130	14	36
Provision for loan, lease and other losses									(5)	(2)	(5)
Total non-interest expense									309	312	165
Income from continuing operations before income taxes									(174)	(296)	(124)
Income tax provision (benefit)									(339)	(350)	(214)
Income from continuing operations, net of tax									165	54	90
Loans held for investment	64				88				64	88	111
Total deposits	$ 20,985				$ 10,762				$ 20,985	$ 10,762	$ 5,516