Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of net periodic benefit cost
Curtailment gain	$ 0.0	$ 0.0	$ 3.3
Pension Benefits
Components of net periodic benefit cost
Curtailment gain	4.6
Other Benefits
Components of net periodic benefit cost
Service cost	0.0	0.0	0.0
Interest cost	0.4	0.4	0.5
Expected return on plan assets	0.0	0.0	0.0
Recognized net actuarial loss	0.0	0.0	0.2
Curtailment gain	0.0	0.0	0.0
Settlement loss	0.0	0.0	0.0
Net periodic pension benefit cost	0.4	0.4	0.7
U.S. Plans | Pension Benefits
Components of net periodic benefit cost
Service cost	3.9	3.9	3.5
Interest cost	20.6	22.9	24.7
Expected return on plan assets	(24.6)	(25.9)	(27.0)
Recognized net actuarial loss	6.6	5.9	5.5
Curtailment gain	0.0	0.0	0.0
Settlement loss	0.0	0.0	0.0
Net periodic pension benefit cost	6.5	6.8	6.7
Foreign Plan [Member] | Pension Benefits
Components of net periodic benefit cost
Service cost	11.0	10.5	5.5
Interest cost	6.2	5.7	2.7
Expected return on plan assets	(10.5)	(4.5)	(3.5)
Recognized net actuarial loss	(0.7)	(0.4)	0.0
Curtailment gain	0.0	(0.1)	4.6
Settlement loss	(2.2)	(0.6)	0.0
Net periodic pension benefit cost	$ 3.8	$ 10.8	$ 0.1