Pension, Post-Retirement and Post-Employment Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net periodic benefit expense:
Net periodic (benefit) cost	$ 1.8	$ (1.0)	$ (0.1)
Pension and SERP Benefits | Domestic
Net periodic benefit expense:
Service cost	0.0	0.0	0.0
Interest cost on the projected benefit obligation	7.2	8.7	8.1
Expected return on plan assets	(10.1)	(9.6)	(10.4)
Amortization of prior service cost	0.0	0.0	0.0
Amortization of actuarial net loss	0.0	0.0	0.0
Plan curtailment	0.0	0.0	0.1
Plan settlement	0.1	0.0	0.2
Net periodic (benefit) cost	(2.8)	(0.9)	(2.0)
Pension and SERP Benefits | Foreign
Net periodic benefit expense:
Service cost	0.7	0.7	1.2
Interest cost on the projected benefit obligation	0.3	0.3	0.3
Expected return on plan assets	(0.1)	(0.1)	(0.1)
Amortization of prior service cost	0.0	0.0	0.0
Amortization of actuarial net loss	0.0	0.1	0.0
Plan curtailment	(0.1)	0.0	0.0
Plan settlement	(0.1)	0.2	0.1
Net periodic (benefit) cost	0.7	1.2	1.5
Post-retirement Medical Benefits | Domestic
Net periodic benefit expense:
Service cost	0.0	0.0	0.0
Interest cost on the projected benefit obligation	0.3	0.4	0.4
Amortization of actuarial net loss	0.0	0.0	0.0
Net periodic (benefit) cost	0.3	0.4	0.4
Post-retirement Medical Benefits | Foreign
Net periodic benefit expense:
Service cost	0.0	0.1	0.1
Interest cost on the projected benefit obligation	0.0	0.1	0.1
Amortization of actuarial net loss	0.0	0.1	0.0
Net periodic (benefit) cost	$ 0.0	$ 0.3	$ 0.2