Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Total	$ 4,829,655	$ 5,457,095
Interest rate contracts [Member]
Derivative [Line Items]
Total	3,338,215	3,993,309
Interest rate contracts [Member] | Futures and forwards [Member]
Derivative [Line Items]
Total	87,406	175,468
Interest rate contracts [Member] | Swaps [Member]
Derivative [Line Items]
Total	3,096,382	3,645,085
Interest rate contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	70,903	85,021
Interest rate contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	83,524	87,735
Foreign exchange contracts [Member]
Derivative [Line Items]
Total	1,160,973	1,024,123
Foreign exchange contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	117,088	82,817
Foreign exchange contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	118,350	84,835
Foreign exchange contracts [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	866,835	804,278
Foreign exchange contracts [Member] | Spot [Member]
Derivative [Line Items]
Total	58,700	52,193
Commodity and Equity Contract [Member]
Derivative [Line Items]
Total	89,730	84,377
Commodity and Equity Contract [Member] | Options written [Member]
Derivative [Line Items]
Total	18,015	21,531
Commodity and Equity Contract [Member] | Options purchased [Member]
Derivative [Line Items]
Total	23,452	21,723
Commodity and Equity Contract [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	48,263	41,123
Credit contracts [Member]
Derivative [Line Items]
Total	$ 240,737	$ 355,286