Derivative Instruments and Hedging Activities - Fair Value and Notional Amounts of Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional or contractual amount	$ 61,950	$ 57,812
Derivatives at Fair Value - Assets	988	1,848
Derivatives at Fair Value - Liabilities	587	400
Derivatives Designated as Accounting Hedges [Member]
Derivative [Line Items]
Notional or contractual amount	34,010	34,139
Derivatives at Fair Value - Assets	367	1,154
Derivatives at Fair Value - Liabilities	299	54
Derivatives Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	29,495	28,927
Derivatives at Fair Value - Assets	352	1,136
Derivatives at Fair Value - Liabilities	239	14
Derivatives Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member] | Fair Value Interest Rate Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	14,970	15,902
Derivatives at Fair Value - Assets	336	1,020
Derivatives at Fair Value - Liabilities	129	0
Derivatives Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member] | Cash Flow Interest Rate Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	14,525	13,025
Derivatives at Fair Value - Assets	16	116
Derivatives at Fair Value - Liabilities	110	14
Derivatives Designated as Accounting Hedges [Member] | Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	4,515	5,212
Derivatives at Fair Value - Assets	15	18
Derivatives at Fair Value - Liabilities	60	40
Derivatives Designated as Accounting Hedges [Member] | Foreign Exchange Contracts [Member] | Cash Flow Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	4,515	5,212
Derivatives at Fair Value - Assets	15	18
Derivatives at Fair Value - Liabilities	60	40
Derivatives not Designated as Accounting Hedges [Member]
Derivative [Line Items]
Notional or contractual amount	27,940	23,673
Derivatives at Fair Value - Assets	621	694
Derivatives at Fair Value - Liabilities	288	346
Derivatives not Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	25,456	21,600
Derivatives at Fair Value - Assets	433	536
Derivatives at Fair Value - Liabilities	222	297
Derivatives not Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member] | MSRs [Member]
Derivative [Line Items]
Notional or contractual amount	262	147
Derivatives at Fair Value - Assets	1	12
Derivatives at Fair Value - Liabilities	3	2
Derivatives not Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member] | Customer Accommodation [Member]
Derivative [Line Items]
Notional or contractual amount	23,126	18,900
Derivatives at Fair Value - Assets	399	479
Derivatives at Fair Value - Liabilities	201	273
Derivatives not Designated as Accounting Hedges [Member] | Interest Rate Contracts [Member] | Other Interest Rate Exposures [Member]
Derivative [Line Items]
Notional or contractual amount	2,068	2,553
Derivatives at Fair Value - Assets	33	45
Derivatives at Fair Value - Liabilities	18	22
Derivatives not Designated as Accounting Hedges [Member] | Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	1,398	1,372
Derivatives at Fair Value - Assets	183	158
Derivatives at Fair Value - Liabilities	46	46
Derivatives not Designated as Accounting Hedges [Member] | Other Contracts [Member]
Derivative [Line Items]
Notional or contractual amount	1,086	701
Derivatives at Fair Value - Assets	5	0
Derivatives at Fair Value - Liabilities	$ 20	$ 3