Loans - Impaired Loans, Excluding Acquired Loans (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
Impaired Financing Receivable:
With an Allowance	$ 1,602		$ 1,602		$ 1,469
Without an Allowance	596		596		445
Total Recorded Investment	2,198		2,198		1,914
Related Allowance	299		299		300
Net Recorded Investment	1,899		1,899		1,614
Unpaid Principal Balance	2,615		2,615		2,296
Average Recorded Investment	2,059	$ 1,926	2,056	$ 1,950
Interest Income Recognized	39	40	120	119
Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	666		666		692
Without an Allowance	0		0		0
Total Recorded Investment	666		666		692
Related Allowance	208		208		219
Net Recorded Investment	458		458		473
Unpaid Principal Balance	646		646		672
Average Recorded Investment	668	717	675	741
Interest Income Recognized	17	17	50	53
Consumer Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	539		539		493
Without an Allowance	352		352		359
Total Recorded Investment	891		891		852
Related Allowance	50		50		42
Net Recorded Investment	841		841		810
Unpaid Principal Balance	1,262		1,262		1,218
Average Recorded Investment	883	829	874	841
Interest Income Recognized	22	20	66	58
Consumer Portfolio Segment [Member] | Auto
Impaired Financing Receivable:
With an Allowance	264		264		230
Without an Allowance	211		211		205
Total Recorded Investment	475		475		435
Related Allowance	22		22		19
Net Recorded Investment	453		453		416
Unpaid Principal Balance	752		752		694
Average Recorded Investment	468	387	456	375
Interest Income Recognized	20	18	61	52
Consumer Portfolio Segment [Member] | Home loan
Impaired Financing Receivable:
With an Allowance	223		223		218
Without an Allowance	134		134		149
Total Recorded Investment	357		357		367
Related Allowance	16		16		17
Net Recorded Investment	341		341		350
Unpaid Principal Balance	450		450		472
Average Recorded Investment	360	382	363	392
Interest Income Recognized	2	1	4	4
Consumer Portfolio Segment [Member] | Retail banking
Impaired Financing Receivable:
With an Allowance	52		52		45
Without an Allowance	7		7		5
Total Recorded Investment	59		59		50
Related Allowance	12		12		6
Net Recorded Investment	47		47		44
Unpaid Principal Balance	60		60		52
Average Recorded Investment	55	60	55	74
Interest Income Recognized	0	1	1	2
Commercial Banking
Impaired Financing Receivable:
With an Allowance	397		397		284
Without an Allowance	244		244		86
Total Recorded Investment	641		641		370
Related Allowance	41		41		39
Net Recorded Investment	600		600		331
Unpaid Principal Balance	707		707		406
Average Recorded Investment	508	380	507	368
Interest Income Recognized	0	3	4	8
Commercial Banking | Total commercial lending
Impaired Financing Receivable:
With an Allowance	392		392		281
Without an Allowance	244		244		81
Total Recorded Investment	636		636		362
Related Allowance	41		41		39
Net Recorded Investment	595		595		323
Unpaid Principal Balance	701		701		396
Average Recorded Investment	500	371	500	360
Interest Income Recognized	0	3	4	8
Commercial Banking | Commercial and multifamily real estate
Impaired Financing Receivable:
With an Allowance	86		86		120
Without an Allowance	4		4		26
Total Recorded Investment	90		90		146
Related Allowance	13		13		23
Net Recorded Investment	77		77		123
Unpaid Principal Balance	93		93		163
Average Recorded Investment	112	196	115	183
Interest Income Recognized	0	2	2	5
Commercial Banking | Commercial and industrial
Impaired Financing Receivable:
With an Allowance	306		306		161
Without an Allowance	240		240		55
Total Recorded Investment	546		546		216
Related Allowance	28		28		16
Net Recorded Investment	518		518		200
Unpaid Principal Balance	608		608		233
Average Recorded Investment	388	175	385	177
Interest Income Recognized	0	1	2	3
Commercial Banking | Small-ticket commercial real estate
Impaired Financing Receivable:
With an Allowance	5		5		3
Without an Allowance	0		0		5
Total Recorded Investment	5		5		8
Related Allowance	0		0		0
Net Recorded Investment	5		5		8
Unpaid Principal Balance	6		6		10
Average Recorded Investment	8	9	7	8
Interest Income Recognized	0	0	0	0
Geographic Distribution, Foreign [Member] | Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	128		128		146
Without an Allowance	0		0		0
Total Recorded Investment	128		128		146
Related Allowance	63		63		74
Net Recorded Investment	65		65		72
Unpaid Principal Balance	124		124		141
Average Recorded Investment	133	159	137	164
Interest Income Recognized	2	3	7	9
Geographic Distribution, Domestic [Member] | Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	538		538		546
Without an Allowance	0		0		0
Total Recorded Investment	538		538		546
Related Allowance	145		145		145
Net Recorded Investment	393		393		401
Unpaid Principal Balance	522		522		$ 531
Average Recorded Investment	535	558	538	577
Interest Income Recognized	$ 15	$ 14	$ 43	$ 44