Loans - TDR Disclosures in Progress Financial Impact of Modification (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Modifications [Line Items]
Total Loans Modified	$ 206	$ 252	$ 671	$ 763
Commercial Banking
Financing Receivable, Modifications [Line Items]
Total Loans Modified	4	37	84	86
Commercial Banking | Total commercial lending
Financing Receivable, Modifications [Line Items]
Total Loans Modified	4	33	83	81
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Modifications [Line Items]
Total Loans Modified	1	18	67	50
Commercial Banking | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Total Loans Modified	3	15	16	31
Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Modifications [Line Items]
Total Loans Modified	0	4	1	5
Credit Card
Financing Receivable, Modifications [Line Items]
Total Loans Modified	103	126	315	378
Credit Card | Domestic
Financing Receivable, Modifications [Line Items]
Total Loans Modified	68	80	199	234
Credit Card | International
Financing Receivable, Modifications [Line Items]
Total Loans Modified	35	46	116	144
Consumer Banking
Financing Receivable, Modifications [Line Items]
Total Loans Modified	99	89	272	299
Consumer Banking | Auto
Financing Receivable, Modifications [Line Items]
Total Loans Modified	88	73	234	196
Consumer Banking | Home loan
Financing Receivable, Modifications [Line Items]
Total Loans Modified	10	10	29	78
Consumer Banking | Retail banking
Financing Receivable, Modifications [Line Items]
Total Loans Modified	1	6	9	25
Reduced Interest Rate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	70.00%	66.00%	65.00%	62.00%
Average Rate Reduction	11.94%	12.79%	12.34%	13.93%
Reduced Interest Rate | Commercial Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	71.00%	32.00%	28.00%	14.00%
Average Rate Reduction	0.85%	1.74%	1.11%	1.74%
Reduced Interest Rate | Commercial Banking | Total commercial lending
Financing Receivable, Modifications [Line Items]
% of TDR Activity	71.00%	36.00%	29.00%	15.00%
Average Rate Reduction	0.85%	1.74%	1.11%	1.74%
Reduced Interest Rate | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	67.00%	31.00%	24.00%
Average Rate Reduction	0.00%	1.74%	1.26%	1.74%
Reduced Interest Rate | Commercial Banking | Commercial and industrial
Financing Receivable, Modifications [Line Items]
% of TDR Activity	96.00%	0.00%	20.00%	0.00%
Average Rate Reduction	0.85%	0.00%	0.18%	0.00%
Reduced Interest Rate | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Average Rate Reduction	0.00%	0.00%	0.00%	0.00%
Reduced Interest Rate | Credit Card
Financing Receivable, Modifications [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	16.12%	16.34%	16.60%	16.85%
Reduced Interest Rate | Credit Card | Domestic
Financing Receivable, Modifications [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	11.52%	11.24%	11.52%	11.90%
Reduced Interest Rate | Credit Card | International
Financing Receivable, Modifications [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	25.41%	25.26%	25.35%	24.89%
Reduced Interest Rate | Consumer Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	40.00%	31.00%	36.00%	27.00%
Average Rate Reduction	1.88%	1.45%	1.41%	1.89%
Reduced Interest Rate | Consumer Banking | Auto
Financing Receivable, Modifications [Line Items]
% of TDR Activity	40.00%	32.00%	37.00%	31.00%
Average Rate Reduction	1.70%	1.04%	1.24%	1.53%
Reduced Interest Rate | Consumer Banking | Home loan
Financing Receivable, Modifications [Line Items]
% of TDR Activity	41.00%	45.00%	34.00%	23.00%
Average Rate Reduction	3.33%	3.33%	2.64%	2.95%
Reduced Interest Rate | Consumer Banking | Retail banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	17.00%	9.00%	8.00%	6.00%
Average Rate Reduction	6.42%	3.89%	5.17%	3.61%
Term Extension
Financing Receivable, Modifications [Line Items]
% of TDR Activity	32.00%	29.00%	36.00%	25.00%
Average Term Extension (Months)	20 months	14 months	16 months	16 months
Term Extension | Commercial Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	74.00%	67.00%	86.00%	69.00%
Average Term Extension (Months)	7 months	21 months	8 months	13 months
Term Extension | Commercial Banking | Total commercial lending
Financing Receivable, Modifications [Line Items]
% of TDR Activity	74.00%	75.00%	87.00%	73.00%
Average Term Extension (Months)	7 months	21 months	8 months	13 months
Term Extension | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	54.00%	92.00%	76.00%
Average Term Extension (Months)	0 months	43 months	7 months	16 months
Term Extension | Commercial Banking | Commercial and industrial
Financing Receivable, Modifications [Line Items]
% of TDR Activity	100.00%	100.00%	67.00%	68.00%
Average Term Extension (Months)	7 months	7 months	10 months	7 months
Term Extension | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months	0 months	0 months
Term Extension | Credit Card
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months	0 months	0 months
Term Extension | Credit Card | Domestic
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months	0 months	0 months
Term Extension | Credit Card | International
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months	0 months	0 months
Term Extension | Consumer Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	63.00%	55.00%	61.00%	45.00%
Average Term Extension (Months)	21 months	11 months	19 months	18 months
Term Extension | Consumer Banking | Auto
Financing Receivable, Modifications [Line Items]
% of TDR Activity	64.00%	54.00%	63.00%	54.00%
Average Term Extension (Months)	9 months	9 months	9 months	9 months
Term Extension | Consumer Banking | Home loan
Financing Receivable, Modifications [Line Items]
% of TDR Activity	52.00%	58.00%	39.00%	18.00%
Average Term Extension (Months)	150 months	25 months	154 months	99 months
Term Extension | Consumer Banking | Retail banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	88.00%	60.00%	72.00%	61.00%
Average Term Extension (Months)	3 months	6 months	7 months	8 months
Balance Reduction
Financing Receivable, Modifications [Line Items]
% of TDR Activity	15.00%	14.00%	13.00%	14.00%
Gross Balance Reduction	28	30	78	82
Balance Reduction | Commercial Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	8.00%	0.00%	5.00%	0.00%
Gross Balance Reduction	0	0	2	0
Balance Reduction | Commercial Banking | Total commercial lending
Financing Receivable, Modifications [Line Items]
% of TDR Activity	8.00%	0.00%	5.00%	0.00%
Gross Balance Reduction	0	0	2	0
Balance Reduction | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	6.00%	0.00%
Gross Balance Reduction	0	0	2	0
Balance Reduction | Commercial Banking | Commercial and industrial
Financing Receivable, Modifications [Line Items]
% of TDR Activity	11.00%	0.00%	2.00%	1.00%
Gross Balance Reduction	0	0	0	0
Balance Reduction | Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Gross Balance Reduction	0	0	0	0
Balance Reduction | Credit Card
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Gross Balance Reduction	0	0	0	0
Balance Reduction | Credit Card | Domestic
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Gross Balance Reduction	0	0	0	0
Balance Reduction | Credit Card | International
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Gross Balance Reduction	0	0	0	0
Balance Reduction | Consumer Banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	31.00%	38.00%	31.00%	35.00%
Gross Balance Reduction	28	30	76	82
Balance Reduction | Consumer Banking | Auto
Financing Receivable, Modifications [Line Items]
% of TDR Activity	35.00%	45.00%	36.00%	45.00%
Gross Balance Reduction	28	30	75	79
Balance Reduction | Consumer Banking | Home loan
Financing Receivable, Modifications [Line Items]
% of TDR Activity	2.00%	13.00%	6.00%	22.00%
Gross Balance Reduction	0	0	1	3
Balance Reduction | Consumer Banking | Retail banking
Financing Receivable, Modifications [Line Items]
% of TDR Activity	0.00%	0.00%	0.00%	0.00%
Gross Balance Reduction	$ 0	$ 0	$ 0	$ 0