Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Total	$ 4,737,184	$ 4,829,655
Interest rate contracts [Member]
Derivative [Line Items]
Total	3,233,922	3,338,215
Interest rate contracts [Member] | Futures and forwards [Member]
Derivative [Line Items]
Total	143,809	87,406
Interest rate contracts [Member] | Swaps [Member]
Derivative [Line Items]
Total	2,913,021	3,096,382
Interest rate contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	77,549	70,903
Interest rate contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	99,543	83,524
Foreign exchange contracts [Member]
Derivative [Line Items]
Total	1,182,589	1,160,973
Foreign exchange contracts [Member] | Options written [Member]
Derivative [Line Items]
Total	105,858	117,088
Foreign exchange contracts [Member] | Options purchased [Member]
Derivative [Line Items]
Total	101,442	118,350
Foreign exchange contracts [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	912,060	866,835
Foreign exchange contracts [Member] | Spot [Member]
Derivative [Line Items]
Total	63,229	58,700
Commodity and Equity Contract [Member]
Derivative [Line Items]
Total	83,124	89,730
Commodity and Equity Contract [Member] | Options written [Member]
Derivative [Line Items]
Total	16,324	18,015
Commodity and Equity Contract [Member] | Options purchased [Member]
Derivative [Line Items]
Total	20,637	23,452
Commodity and Equity Contract [Member] | Swaps, futures and forwards [Member]
Derivative [Line Items]
Total	46,163	48,263
Credit contracts [Member]
Derivative [Line Items]
Total	$ 237,549	$ 240,737