Loans - Loan Portfolio Composition and Aging Analysis (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 01, 2015	Dec. 31, 2013
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 203,438	$ 178,746
Past due	6,895	6,070
Loans held for investment	$ 229,851	$ 208,316		$ 197,199
Financing Receivable, Recorded Investment, Aging, Percent of Total Loan [Abstract]
Financing Receivable, Percent Current	88.51%	85.81%
Total Delinquent Loans (as percent)	3.00%	2.91%
Total Loans (as percent)	100.00%	100.00%
Loans and Leases Receivable, Deferred Income	$ 989	$ 1,100
Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	92,857	83,021
Past due	3,268	2,832
Loans held for investment	96,125	85,876
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	48,528	45,130
Past due	3,284	3,024
Loans held for investment	70,372	71,439
Consumer Portfolio Segment [Member] | Auto
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	38,549	35,142
Past due	3,000	2,682
Loans held for investment	41,549	37,824
Consumer Portfolio Segment [Member] | Home loan
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,465	6,492
Past due	235	302
Loans held for investment	25,227	30,035
Consumer Portfolio Segment [Member] | Retail banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	3,514	3,496
Past due	49	40
Loans held for investment	3,596	3,580
Commercial Banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	61,976	50,498
Past due	332	200
Loans held for investment	63,266	50,890
Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	61,369	49,727
Past due	326	190
Loans held for investment	62,653	50,109
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	25,449	22,974
Past due	38	117
Loans held for investment	25,518	23,137
Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	35,920	26,753
Past due	288	73
Loans held for investment	37,135	26,972
Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	607	771
Past due	6	10
Loans held for investment	613	781
Other
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	77	97
Past due	11	14
Loans held for investment	88	111
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	$ 19,518	$ 23,500
Financing Receivable, Recorded Investment, Aging, Percent of Total Loan [Abstract]
Total Loans (as percent)	8.49%	11.28%
Receivables Acquired with Deteriorated Credit Quality [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	$ 0	$ 23
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	18,560	23,285
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Portfolio Segment [Member] | Auto
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Portfolio Segment [Member] | Home loan
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	18,527	23,241
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Portfolio Segment [Member] | Retail banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	33	44
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	958	192
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	958	192
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	31	46
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	927	146
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Other
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	0	0
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 3,069	$ 2,841
Financing Receivable, Recorded Investment, Aging, Percent of Total Loan [Abstract]
Total Delinquent Loans (as percent)	1.33%	1.36%
Financing Receivables, 30 to 59 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 1,016	$ 904
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	1,963	1,825
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Auto
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	1,901	1,751
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home loan
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	41	57
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Retail banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	21	17
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	88	109
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	85	103
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	34	74
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	51	29
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	3	6
Financing Receivables, 30 to 59 Days Past Due [Member] | Other
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	2	3
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 1,668	$ 1,424
Financing Receivable, Recorded Investment, Aging, Percent of Total Loan [Abstract]
Total Delinquent Loans (as percent)	0.73%	0.68%
Financing Receivables, 60 to 89 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 725	$ 636
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	906	768
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Auto
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	880	734
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home loan
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	18	27
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Retail banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	8	7
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	35	18
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	34	17
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	0	7
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	34	10
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	1	1
Financing Receivables, 60 to 89 Days Past Due [Member] | Other
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	2	2
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 2,158	$ 1,805
Financing Receivable, Recorded Investment, Aging, Percent of Total Loan [Abstract]
Total Delinquent Loans (as percent)	0.94%	0.87%
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 1,527	$ 1,292
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	415	431
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Auto
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	219	197
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home loan
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	176	218
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Retail banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	20	16
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Banking
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	209	73
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	207	70
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	4	36
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	203	34
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	2	3
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Other
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	7	9
Geographic Distribution, Domestic [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	84,954	75,143
Past due	2,985	2,538
Loans held for investment	87,939	77,704
Geographic Distribution, Domestic [Member] | Credit Card Portfolio Segment [Member] | Installment loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Gross	16	144
Geographic Distribution, Domestic [Member] | Receivables Acquired with Deteriorated Credit Quality [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	0	23
Geographic Distribution, Domestic [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	906	790
Geographic Distribution, Domestic [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	658	567
Geographic Distribution, Domestic [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	1,421	1,181
Geographic Distribution, Foreign [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	7,903	7,878
Past due	283	294
Loans held for investment	8,186	8,172
Geographic Distribution, Foreign [Member] | Receivables Acquired with Deteriorated Credit Quality [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	0	0
Geographic Distribution, Foreign [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	110	114
Geographic Distribution, Foreign [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	67	69
Geographic Distribution, Foreign [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Credit Card Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Past due	$ 106	$ 111
GE Healthcare [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Business Combination, Recognized identifiable Assets Acquired and Liabilities Assumed, Loan held for investment			$ 8,200
Business Combination, Recognized identifiable Assets Acquired and Liabilities Assumed, Loan held for investment Excluding 03-3 loans			7,400
GE Healthcare [Member] | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Business Combination, Recognized identifiable Assets Acquired and Liabilities Assumed, Loan held for investment			$ 847