Pension Plans - Retirement Plan Expense (Details) - Foreign Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Company defined benefit plans:
Service cost	$ 3.1	$ 2.4	$ 2.6
Interest cost	2.1	2.4	2.3
Expected return on plan assets	(0.8)	(0.9)	(0.7)
Net amortization	0.4	0.0	0.0
Net periodic pension expense	4.8	3.9	4.2
Curtailment	0.0	0.0	(1.3)
Defined contribution plans	2.1	2.8	3.7
Total	$ 6.9	$ 6.7	$ 6.6