Ineffectiveness Related to Derivatives and Hedging Relationships Recorded in Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness related to derivatives and hedging relationships	$ (0.1)		$ (6.2)		$ (6.1)
Securities Investment
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness related to derivatives and hedging relationships	3.4		(3.5)		(0.3)
Deposits and long term debt
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness related to derivatives and hedging relationships	(3.5)		(2.7)		(5.8)
Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness related to derivatives and hedging relationships	0.1		(0.1)		(0.1)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness related to derivatives and hedging relationships	$ (0.1)	[1]	$ 0.1	[1]	$ 0.1	[1]

[1] Includes ineffectiveness recorded on foreign exchange hedges.