Loans and Allowance for Credit Losses - Impaired Loans Average Recorded Investment and Interest Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 7,130	$ 7,639	$ 7,346	$ 7,752
Interest Income Recognized	81	85	270	227
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	380	413	384	496
Interest Income Recognized	5	6	24	11
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	819	1,250	950	1,371
Interest Income Recognized	6	12	27	29
Residential Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,765	2,752	2,744	2,692
Interest Income Recognized	32	31	99	87
Credit Card [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	347	495	380	529
Interest Income Recognized	3	6	12	22
Other Retail [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	417	354	431	259
Interest Income Recognized	7	3	19	7
Total Impaired Loans, Excluding GNMA and Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	4,728	5,264	4,889	5,347
Interest Income Recognized	53	58	181	156
Loans Purchased from GNMA Mortgage Pools [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,883	1,492	1,869	1,363
Interest Income Recognized	22	20	68	51
Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	519	883	588	1,042
Interest Income Recognized	$ 6	$ 7	$ 21	$ 20