Components of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (283.0)	$ (345.6)
Net Change	(1.1)	69.3
Ending Balance	(284.1)	(276.3)
Net Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	101.0	39.8
Net Change	1.3	20.0
Ending Balance	102.3	59.8
Net Unrealized Gains (Losses) on Cash Flow Hedge Designations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1.4)	(7.0)
Net Change	(5.2)	11.3
Ending Balance	(6.6)	4.3
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	10.5	(9.5)
Net Change	(4.2)	15.8
Ending Balance	6.3	6.3
Net Pension and Other Postretirement Benefit Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(393.1)	(368.9)
Net Change	7.0	22.2
Ending Balance	$ (386.1)	$ (346.7)