Accumulated Other Comprehensive Income Activity (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (180.7)
OCI excluding reclassifications	(102.1)
Reclassifications to earnings	(79.3)
OCI, net of tax	(181.4)	$ (122.1)	$ (5.2)
Ending Balance	(362.1)	(180.7)
Accrued Benefit Cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(54.6)
OCI excluding reclassifications	40.7
Reclassifications to earnings	(39.7)
OCI, net of tax	1.0
Ending Balance	(53.6)	(54.6)
Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	13.4
OCI excluding reclassifications	42.9
Reclassifications to earnings	(39.6)
OCI, net of tax	3.3
Ending Balance	16.7	13.4
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(139.5)
OCI excluding reclassifications	(185.7)
Reclassifications to earnings	0.0
OCI, net of tax	(185.7)
Ending Balance	$ (325.2)	$ (139.5)