Reclassifications out of Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 793.9
Other comprehensive income before reclassifications	7.3
Amounts reclassified from AOCL	0.2
Total other comprehensive income	7.5	$ 4.5
Ending Balance	824.4
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(38.5)
Ending Balance	(31.0)
Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1.2
Other comprehensive income before reclassifications	0.9
Amounts reclassified from AOCL	0.0
Total other comprehensive income	0.9
Ending Balance	2.1
Defined Benefit Pension Plan Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3.2)
Other comprehensive income before reclassifications	0.0
Amounts reclassified from AOCL	0.2
Total other comprehensive income	0.2
Ending Balance	(3.0)
Foreign Currency Translation Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(36.5)
Other comprehensive income before reclassifications	6.4
Amounts reclassified from AOCL	0.0
Total other comprehensive income	6.4
Ending Balance	$ (30.1)