Accumulated Other Comprehensive Income - Changes in Components of Accumulated Other Comprehensive Income, Net of Tax (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Income, Beginning Balance	$ (434.0)
Accumulated Other Comprehensive Income, Ending Balance	(264.4)
Foreign Currency Translation [Member]
Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Income, Beginning Balance	(323.4)
AOCI before reclassifications	238.2
Accumulated Other Comprehensive Income, Ending Balance	(85.2)
Unrealized (Losses) Gains on Securities [Member]
Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Income, Beginning Balance	(0.1)
Accumulated Other Comprehensive Income, Ending Balance	(0.1)
Defined Benefit Plan Items [Member]
Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Income, Beginning Balance	(142.8)
AOCI before reclassifications	(7.4)
Reclassifications	3.4
Accumulated Other Comprehensive Income, Ending Balance	(146.8)
Cash Flow Hedges [Member]
Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Income, Beginning Balance	32.3
AOCI before reclassifications	(51.1)
Reclassifications	(13.5)
Accumulated Other Comprehensive Income, Ending Balance	$ (32.3)