Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) (USD $) In Billions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Interest rate	$ 3,537.7	$ 3,244.0
Foreign Exchange	1,107.1	910.4
Commodities, equities and precious metals	95.3	90.5
Credit derivatives	463.5	484.9
Total	5,203.6	4,729.8
Futures and forwards [Member]
Derivative [Line Items]
Interest rate	242.7	313.9
Swaps [Member]
Derivative [Line Items]
Interest rate	3,077.2	2,842.6
Options written [Member]
Derivative [Line Items]
Interest rate	110.0	43.3
Foreign Exchange	74.6	54.9
Commodities, equities and precious metals	22.7	21.0
Options purchased [Member]
Derivative [Line Items]
Interest rate	107.8	44.2
Foreign Exchange	0	55.5
Commodities, equities and precious metals	23.2	21.4
Swaps, futures and forwards [Member]
Derivative [Line Items]
Foreign Exchange	946.5	743.7
Commodities, equities and precious metals	49.4	48.1
Spot [Member]
Derivative [Line Items]
Foreign Exchange	$ 86.0	$ 56.3