Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Total	$ 5,070,299	$ 5,457,095
Interest rate contracts [Member]
Derivative [Line Items]
Total	3,400,586	3,993,309
Interest rate contracts [Member] | Futures and forwards [Member]
Derivative [Line Items]
Total	220,669	175,468
Interest rate contracts [Member] | Swaps [Member]
Derivative [Line Items]
Total	3,056,578	3,645,085
Interest rate contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	53,332	85,021
Interest rate contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	70,007	87,735
Foreign exchange contracts [Member]
Derivative [Line Items]
Total	1,237,356	1,024,123
Foreign exchange contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	131,705	82,817
Foreign exchange contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	133,386	84,835
Foreign exchange contracts [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	892,385	804,278
Foreign exchange contracts [Member] | Spot [Member]
Derivative [Line Items]
Total	79,880	52,193
Commodity and Equity Contract [Member]
Derivative [Line Items]
Total	85,563	84,377
Commodity and Equity Contract [Member] | Options written [Member]
Derivative [Line Items]
Total	14,740	21,531
Commodity and Equity Contract [Member] | Options purchased [Member]
Derivative [Line Items]
Total	20,491	21,723
Commodity and Equity Contract [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	50,332	41,123
Credit contracts [Member]
Derivative [Line Items]
Total	$ 346,794	$ 355,286