Pensions - Summary of Changes in Projected Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. Benefit Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	$ 180.6	$ 174.3
Service cost	0.0	0.0	$ 0.0
Interest cost	7.6	7.8	7.6
Actuarial loss (gain)	12.9	7.7
Benefits and expenses paid	(8.4)	(9.2)
Settlement payments	(13.7)	0.0
Foreign currency translation	0.0	0.0
Benefit obligation, end of year	179.0	180.6	174.3
Accumulated benefit obligation, end of year	179.0	180.6
Non-U.S. Benefit Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	51.7	55.7
Service cost	0.2	0.2	0.2
Interest cost	1.4	1.8	2.1
Actuarial loss (gain)	(0.1)	7.8
Benefits and expenses paid	(3.3)	(4.2)
Settlement payments	0.0	0.0
Foreign currency translation	4.8	(9.6)
Benefit obligation, end of year	54.7	51.7	$ 55.7
Accumulated benefit obligation, end of year	$ 54.7	$ 51.7