Components of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (345.6)	$ (305.3)
Net Change	69.3	25.7
Ending Balance	(276.3)	(279.6)
Net Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	39.8	(13.5)
Net Change	20.0	3.4
Ending Balance	59.8	(10.1)
Net Unrealized Gains (Losses) on Cash Flow Hedge Designations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(7.0)	11.4
Net Change	11.3	9.0
Ending Balance	4.3	20.4
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9.5)	(7.0)
Net Change	15.8	7.2
Ending Balance	6.3	0.2
Net Pension and Other Postretirement Benefit Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(368.9)	(296.2)
Net Change	22.2	6.1
Ending Balance	$ (346.7)	$ (290.1)