Benefit Plans - Amounts Recorded in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	$ (285.6)	$ (253.4)
Post-retirement
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Assets, Noncurrent	0.0	0.0
Current liabilities	(3.1)	(3.2)
Non-current liabilities	(32.5)	(33.7)
Benefit obligations in excess of the fair value of plan assets	(35.6)	(36.9)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Assets, Noncurrent	3.8	3.2
Current liabilities	(3.6)	(2.9)
Non-current liabilities	(156.2)	(141.4)
Benefit obligations in excess of the fair value of plan assets	(156.0)	(141.1)
U.S.
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Assets, Noncurrent	0.0	0.8
Current liabilities	(6.0)	(4.4)
Non-current liabilities	(82.5)	(65.3)
Benefit obligations in excess of the fair value of plan assets	$ (88.5)	$ (68.9)