Loans - TDR - Subsequent Defaults of Completed TDR Modifications (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	20,698	25,140	64,784	72,059
Total Loans	$ 59	$ 88	$ 202	$ 247
Credit Card
Financing Receivable, Modifications [Line Items]
Number of Contracts	18,991	22,755	60,015	64,726
Total Loans	40	52	131	157
Credit Card | Domestic
Financing Receivable, Modifications [Line Items]
Number of Contracts	9,882	10,114	30,502	28,957
Total Loans	16	16	47	53
Credit Card | International
Financing Receivable, Modifications [Line Items]
Number of Contracts	9,109	12,641	29,513	35,769
Total Loans	24	36	84	104
Consumer Banking
Financing Receivable, Modifications [Line Items]
Number of Contracts	1,689	2,369	4,737	7,302
Total Loans	19	21	61	56
Consumer Banking | Auto
Financing Receivable, Modifications [Line Items]
Number of Contracts	1,674	2,321	4,672	7,178
Total Loans	18	17	49	49
Consumer Banking | Home loan
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	7	12	25
Total Loans	1	1	3	2
Consumer Banking | Retail banking
Financing Receivable, Modifications [Line Items]
Number of Contracts	13	41	53	99
Total Loans	0	3	9	5
Commercial Banking
Financing Receivable, Modifications [Line Items]
Number of Contracts	18	16	32	31
Total Loans	0	15	10	34
Commercial Banking | Total commercial lending
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	16	6	30
Total Loans	0	15	7	34
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	3	4	10
Total Loans	0	4	6	15
Commercial Banking | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	13	2	20
Total Loans	0	11	1	19
Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	18	0	26	1
Total Loans	$ 0	$ 0	$ 3	$ 0