Accumulated Other Comprehensive (Loss) Income - Changes in Components of Other Comprehensive Income, Net of Tax (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income, Beginning Balance	$ (434.0)
Other Comprehensive Income, Ending Balance	(83.2)
Foreign Currency Translation [Member]
Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income, Beginning Balance	(323.5)
OCI before reclassifications	445.0
Other Comprehensive Income, Ending Balance	121.5
Defined Benefit Plan Items [Member]
Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income, Beginning Balance	(142.8)
OCI before reclassifications	(2.7)
Reclassifications	7.3
Other Comprehensive Income, Ending Balance	(138.2)
Cash Flow Hedges [Member]
Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income, Beginning Balance	32.3
OCI before reclassifications	(95.0)
Reclassifications	(3.8)
Other Comprehensive Income, Ending Balance	$ (66.5)