Additional Information on Impaired Loans (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 7,639	$ 7,179	$ 7,752	$ 6,236
Interest Income Recognized	85	56	227	157
Commercial Loan
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	413	536	496	529
Interest Income Recognized	6	4	11	7
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,250	1,558	1,371	1,519
Interest Income Recognized	12	6	29	10
Residential Mortgage
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,752	2,573	2,692	2,540
Interest Income Recognized	31	24	87	74
Credit Card
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	495	492	529	471
Interest Income Recognized	6	4	22	10
Other Retail
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	354	165	259	160
Interest Income Recognized	3	1	7	3
Total loans, excluding GNMA and covered loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5,264	5,324	5,347	5,219
Interest Income Recognized	58	39	156	104
Loans purchased from GNMA
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,492	710	1,363	433
Interest Income Recognized	20	10	51	19
Covered loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	883	1,145	1,042	584
Interest Income Recognized	$ 7	$ 7	$ 20	$ 34