Derivative Instruments - Customer-Related Derivative Positions of Company (Detail) (Customer-Related Positions [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional Value, Assets	$ 31,076	$ 33,440
Fair Value, Assets	1,467	1,443
Notional Value, Liabilities	31,356	33,013
Fair Value, Liabilities	1,397	1,365
Interest rate contracts [Member] | Receive fixed/pay floating swaps [Member]
Derivative [Line Items]
Notional Value, Assets	16,441	16,671
Fair Value, Assets	985	1,085
Derivative Asset Average Remaining Maturity Period	4.93	4.78
Notional Value, Liabilities	1,383	1,090
Fair Value, Liabilities	18	15
Derivative Liability Average Remaining Maturity Period	7.09	9.30
Interest rate contracts [Member] | Pay fixed/receive floating swaps [Member]
Derivative [Line Items]
Notional Value, Assets	1,169	928
Fair Value, Assets	17	14
Derivative Asset Average Remaining Maturity Period	8.24	11.12
Notional Value, Liabilities	16,745	16,923
Fair Value, Liabilities	942	1,042
Derivative Liability Average Remaining Maturity Period	4.90	4.74
Interest rate contracts [Member] | Purchased options [Member]
Derivative [Line Items]
Notional Value, Assets	3,171	3,046
Fair Value, Assets	18	16
Derivative Asset Average Remaining Maturity Period	4.96	5.24
Notional Value, Liabilities	28	28
Derivative Liability Average Remaining Maturity Period	4.17	4.42
Interest rate contracts [Member] | Written options [Member]
Derivative [Line Items]
Notional Value, Assets	28	286
Derivative Asset Average Remaining Maturity Period	4.17	0.75
Notional Value, Liabilities	3,124	2,788
Fair Value, Liabilities	18	16
Derivative Liability Average Remaining Maturity Period	5.02	5.68
Foreign exchange contract [Member] | Forwards, spots and swaps [Member]
Derivative [Line Items]
Notional Value, Assets	10,018	12,186
Fair Value, Assets	443	322
Derivative Asset Average Remaining Maturity Period	0.56	0.43
Notional Value, Liabilities	9,827	11,861
Fair Value, Liabilities	415	286
Derivative Liability Average Remaining Maturity Period	0.55	0.44
Foreign exchange contract [Member] | Purchased options [Member]
Derivative [Line Items]
Notional Value, Assets	249	323
Fair Value, Assets	4	6
Derivative Asset Average Remaining Maturity Period	0.48	0.55
Foreign exchange contract [Member] | Written options [Member]
Derivative [Line Items]
Notional Value, Liabilities	249	323
Fair Value, Liabilities	$ 4	$ 6
Derivative Liability Average Remaining Maturity Period	0.48	0.55