Gains and Losses Recorded in Consolidated Statement of Income Related to Client Related and Trading Derivative Financial Instruments (Detail) (Client Related and Trading, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Gain/(Loss) Recognized in Income	$ 55.0	$ 75.1	$ 107.0	$ 137.8
Foreign Exchange Contracts | Foreign Exchange Trading Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Gain/(Loss) Recognized in Income	52.9	71.3	103.0	130.8
Interest Rate Contracts | Security Commissions and Trading Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Gain/(Loss) Recognized in Income	$ 2.1	$ 3.8	$ 4.0	$ 7.0