Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Total	$ 4,542,542	$ 4,829,655
Interest rate contracts [Member]
Derivative [Line Items]
Total	3,055,680	3,338,215
Interest rate contracts [Member] | Futures and forwards [Member]
Derivative [Line Items]
Total	156,332	87,406
Interest rate contracts [Member] | Swaps [Member]
Derivative [Line Items]
Total	2,722,290	3,096,382
Interest rate contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	84,752	70,903
Interest rate contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	92,306	83,524
Foreign exchange contracts [Member]
Derivative [Line Items]
Total	1,191,781	1,160,973
Foreign exchange contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	96,815	117,088
Foreign exchange contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	93,521	118,350
Foreign exchange contracts [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	931,756	866,835
Foreign exchange contracts [Member] | Spot [Member]
Derivative [Line Items]
Total	69,689	58,700
Commodities, equities and precious metals contracts [Member]
Derivative [Line Items]
Total	85,137	89,730
Commodities, equities and precious metals contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	16,223	18,015
Commodities, equities and precious metals contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	29,812	23,452
Commodities, equities and precious metals contracts [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	39,102	48,263
Credit contracts [Member]
Derivative [Line Items]
Total	$ 209,944	$ 240,737