Retirement and Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Domestic Plan
Components of the net periodic cost for retirement and postretirement benefits
Service cost	$ 5.6	$ 6.0
Interest cost	4.5	4.0
Expected return on plan assets	(6.5)	(6.5)
Amortization of prior service cost	0.0	0.0
Amortization of unrecognized net loss (gain)	0.9	1.4
Net periodic cost recognized	4.5	4.9
Foreign Plan
Components of the net periodic cost for retirement and postretirement benefits
Service cost	1.5	1.8
Interest cost	2.2	2.3
Expected return on plan assets	(1.9)	(2.2)
Amortization of prior service cost	0.1	0.0
Amortization of unrecognized net loss (gain)	0.7	0.9
Net periodic cost recognized	2.6	2.8
Postretirement Medical Benefits
Components of the net periodic cost for retirement and postretirement benefits
Service cost	0.0	0.0
Interest cost	0.2	0.2
Expected return on plan assets	0.0	0.0
Amortization of prior service cost	0.0	0.0
Amortization of unrecognized net loss (gain)	(0.1)	(0.1)
Net periodic cost recognized	$ 0.1	$ 0.1