Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Derivatives, Fair Value [Line Items]
Derivative Asset, Netting adjustments	$ (1,376)	$ (1,452)	$ (1,605)
Derivative Asset, Netting adjustments	(1,376)	(1,452)	(1,605)
Derivative Liability, Netting adjustments	(905)	(978)	(1,064)
Notional Amount	81,381	74,544	71,660
Derivative Asset	771	945	940
Derivative Liability	657	1,026	1,141
Designated
Derivatives, Fair Value [Line Items]
Notional Amount	16,860	15,621	13,237
Derivative Asset	604	589	613
Derivative Liability	41	174	267
Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	64,521	58,923	58,423
Derivative Asset	1,543	1,808	1,932
Derivative Liability	1,521	1,830	1,938
Interest rate [Member] | Designated
Derivatives, Fair Value [Line Items]
Notional Amount	16,596	15,067	12,139
Derivative Asset	604	589	613
Derivative Liability	31	27	29
Interest rate [Member] | Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	55,391	48,537	47,302
Derivative Asset	1,260	1,364	1,429
Derivative Liability	1,252	1,371	1,447
Foreign Exchange [Member] | Designated
Derivatives, Fair Value [Line Items]
Notional Amount	264	554	1,098
Derivative Liability	10	147	238
Foreign Exchange [Member] | Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	5,126	5,549	6,312
Derivative Asset	81	151	190
Derivative Liability	73	141	176
Energy and commodity [Member] | Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	1,749	1,610	1,835
Derivative Asset	183	253	270
Derivative Liability	178	253	275
Credit [Member] | Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	2,242	3,210	2,951
Derivative Asset	19	37	40
Derivative Liability	18	62	37
Equity [Member] | Nondesignated
Derivatives, Fair Value [Line Items]
Notional Amount	13	17	23
Derivative Asset		3	3
Derivative Liability		$ 3	$ 3