Loans Modified as TDRs (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 SecurityLoan	Sep. 30, 2011 SecurityLoan	Sep. 30, 2012 SecurityLoan	Sep. 30, 2011 SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans	29,834	20,075	63,784	57,840
Pre-Modification Outstanding Loan Balance	$ 1,409	$ 900	$ 2,905	$ 3,321
Post-Modification Outstanding Loan Balance	1,332	883	2,817	3,312
Commercial Loan
Financing Receivable, Modifications [Line Items]
Number of Loans	1,754	1,137	4,081	3,984
Pre-Modification Outstanding Loan Balance	54	89	215	337
Post-Modification Outstanding Loan Balance	58	74	195	310
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans	63	115	245	380
Pre-Modification Outstanding Loan Balance	91	124	416	906
Post-Modification Outstanding Loan Balance	80	115	390	896
Residential Mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans	2,717	748	3,788	2,571
Pre-Modification Outstanding Loan Balance	344	155	529	515
Post-Modification Outstanding Loan Balance	336	156	517	512
Credit Card
Financing Receivable, Modifications [Line Items]
Number of Loans	14,137	14,942	39,040	41,610
Pre-Modification Outstanding Loan Balance	52	78	189	239
Post-Modification Outstanding Loan Balance	67	77	203	238
Other Retail
Financing Receivable, Modifications [Line Items]
Number of Loans	6,231	956	8,028	3,020
Pre-Modification Outstanding Loan Balance	159	15	194	55
Post-Modification Outstanding Loan Balance	156	16	191	55
Total loans, excluding GNMA and covered loans
Financing Receivable, Modifications [Line Items]
Number of Loans	24,902	17,898	55,182	51,565
Pre-Modification Outstanding Loan Balance	700	461	1,543	2,052
Post-Modification Outstanding Loan Balance	697	438	1,496	2,011
Loans purchased from GNMA
Financing Receivable, Modifications [Line Items]
Number of Loans	4,859	2,110	8,436	6,042
Pre-Modification Outstanding Loan Balance	660	291	1,116	813
Post-Modification Outstanding Loan Balance	589	312	1,087	871
Covered loans
Financing Receivable, Modifications [Line Items]
Number of Loans	73	67	166	233
Pre-Modification Outstanding Loan Balance	49	148	246	456
Post-Modification Outstanding Loan Balance	$ 46	$ 133	$ 234	$ 430