Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of net periodic benefit cost
Curtailment gain	$ 0.0	$ 3.3	$ 0.0
Pension Benefits
Components of net periodic benefit cost
Curtailment gain	$ 4.6
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.24%	4.62%
Components of net periodic benefit cost
Service cost	$ 0.0	$ 0.0	0.0
Interest cost	0.4	0.5	0.6
Expected return on plan assets	0.0	0.0	0.0
Amortization of prior service cost	0.0	0.0	(0.2)
Recognized net actuarial loss	0.0	0.2	0.3
Curtailment gain	0.0	0.0	0.0
Settlement loss	0.0	0.0	0.0
Net periodic pension benefit cost	$ 0.4	$ 0.7	0.7
U.S. Plans | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.24%	4.62%
Components of net periodic benefit cost
Service cost	$ 3.9	$ 3.5	3.6
Interest cost	22.9	24.7	23.8
Expected return on plan assets	(25.9)	(27.0)	(27.0)
Amortization of prior service cost	0.0	0.0	0.0
Recognized net actuarial loss	5.9	5.5	6.6
Curtailment gain	0.0	0.0	0.0
Settlement loss	0.0	0.0	0.0
Net periodic pension benefit cost	$ 6.8	$ 6.7	7.0
Foreign Plan [Member] | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	1.47%	1.16%
Components of net periodic benefit cost
Service cost	$ 10.5	$ 5.5	0.1
Interest cost	5.7	2.7	0.0
Expected return on plan assets	(4.5)	(3.5)	0.0
Amortization of prior service cost	0.0	0.0	0.0
Recognized net actuarial loss	(0.4)	0.0	0.0
Curtailment gain	(0.1)	4.6	0.0
Settlement loss	(0.6)	0.0	0.0
Net periodic pension benefit cost	$ 10.8	$ 0.1	$ 0.1