Loans - Individually Impaired Loans, Excluding Acquired Loans (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Impaired Loans By Type [Line Items]
Total Recorded Investment	$ 1,831	$ 1,980
Related Allowance	326	426
Net Recorded Investment	1,505	1,554
Unpaid Principal Balance	2,264	2,346
Average Recorded Investment	1,916	1,820
Interest Income Recognized	112	133
Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	646	569
Related Allowance	51	40
Net Recorded Investment	595	529
Unpaid Principal Balance	1,051	891
Average Recorded Investment	608	338
Interest Income Recognized	53	38
Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	394	538
Related Allowance	26	55
Net Recorded Investment	368	483
Unpaid Principal Balance	445	613
Average Recorded Investment	483	603
Interest Income Recognized	1	14
With an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	1,441	1,571
With an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	448	375
With an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	202	323
Without an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	390	409
Without an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	198	194
Without an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	192	215
Domestic Credit Card [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	623	701
Related Allowance	145	230
Net Recorded Investment	478	471
Unpaid Principal Balance	607	678
Average Recorded Investment	656	687
Interest Income Recognized	50	70
Domestic Credit Card [Member] | With an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	623	701
Domestic Credit Card [Member] | Without an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	0	0
International Credit Card [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	168	172
Related Allowance	104	101
Net Recorded Investment	64	71
Unpaid Principal Balance	161	164
Average Recorded Investment	169	192
Interest Income Recognized	8	11
International Credit Card [Member] | With an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	168	172
International Credit Card [Member] | Without an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	0	0
Credit Card and Installment Loans [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	791	873
Related Allowance	249	331
Net Recorded Investment	542	542
Unpaid Principal Balance	768	842
Average Recorded Investment	825	879
Interest Income Recognized	58	81
Credit Card and Installment Loans [Member] | With an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	791	873
Credit Card and Installment Loans [Member] | Without an Allowance [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	0	0
Auto [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	338	328
Related Allowance	16	20
Net Recorded Investment	322	308
Unpaid Principal Balance	563	606
Average Recorded Investment	330	130
Interest Income Recognized	46	31
Auto [Member] | With an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	163	169
Auto [Member] | Without an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	175	159
Home Loan [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	217	145
Related Allowance	17	13
Net Recorded Investment	200	132
Unpaid Principal Balance	255	167
Average Recorded Investment	184	120
Interest Income Recognized	5	4
Home Loan [Member] | With an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	217	145
Home Loan [Member] | Without an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	0	0
Retail Banking [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	91	96
Related Allowance	18	7
Net Recorded Investment	73	89
Unpaid Principal Balance	233	118
Average Recorded Investment	94	88
Interest Income Recognized	2	3
Retail Banking [Member] | With an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	68	61
Retail Banking [Member] | Without an Allowance [Member] | Consumer Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	23	35
Commercial and Multifamily Real Estate [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	171	280
Related Allowance	4	32
Net Recorded Investment	167	248
Unpaid Principal Balance	154	315
Average Recorded Investment	237	353
Interest Income Recognized	0	8
Commercial and Multifamily Real Estate [Member] | With an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	78	168
Commercial and Multifamily Real Estate [Member] | Without an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	93	112
Commercial and Industrial [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	207	244
Related Allowance	15	22
Net Recorded Investment	192	222
Unpaid Principal Balance	267	277
Average Recorded Investment	227	227
Interest Income Recognized	1	6
Commercial and Industrial [Member] | With an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	108	152
Commercial and Industrial [Member] | Without an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	99	92
Total Commercial Lending [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	378	524
Related Allowance	19	54
Net Recorded Investment	359	470
Unpaid Principal Balance	421	592
Average Recorded Investment	464	580
Interest Income Recognized	1	14
Total Commercial Lending [Member] | With an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	186	320
Total Commercial Lending [Member] | Without an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	192	204
Small-Ticket Commercial Real Estate [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	16	14
Related Allowance	7	1
Net Recorded Investment	9	13
Unpaid Principal Balance	24	21
Average Recorded Investment	19	23
Interest Income Recognized	0	0
Small-Ticket Commercial Real Estate [Member] | With an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	16	3
Small-Ticket Commercial Real Estate [Member] | Without an Allowance [Member] | Commercial Banking [Member]
Impaired Loans By Type [Line Items]
Total Recorded Investment	$ 0	$ 11