Notional and Fair Value Amounts of Client-related and Trading Derivative Financial Instruments (Detail) - Client Related and Trading - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Value	$ 270,540.1	$ 262,922.5
Fair Value Asset	2,547.8	4,255.0
Fair Value Liability	2,509.8	4,173.3
Foreign Exchange Contracts
Derivative [Line Items]
Notional Value	264,964.1	257,568.7
Fair Value Asset	2,451.3	4,149.5
Fair Value Liability	2,416.7	4,072.0
Interest Rate Contracts
Derivative [Line Items]
Notional Value	5,576.0	5,353.8
Fair Value Asset	96.5	105.5
Fair Value Liability	$ 93.1	$ 101.3