Accumulated Other Comprehensive Income Activity (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ (180.7)
OCI excluding reclassifications			(142.1)
Reclassifications to earnings			(10.8)
Subtotal OCI, net of tax	$ (71.8)	$ (53.5)	(152.9)	$ (50.3)
Ending Balance	(333.6)		(333.6)
Accrued Benefit Cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(54.6)
OCI excluding reclassifications			0.7
Reclassifications to earnings			3.2
Subtotal OCI, net of tax			3.9
Ending Balance	(50.7)		(50.7)
Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			13.4
OCI excluding reclassifications			11.2
Reclassifications to earnings			(14.0)
Subtotal OCI, net of tax			(2.8)
Ending Balance	10.6		10.6
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(139.5)
OCI excluding reclassifications			(154.0)
Reclassifications to earnings			0.0
Subtotal OCI, net of tax			(154.0)
Ending Balance	$ (293.5)		$ (293.5)