Pension, Post-Retirement and Post-Employment Plans - Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet
Pension and post-retirement benefits	$ 43.3	$ 50.8
Domestic | Pension and SERP Benefits
Balance Sheet
Accrued expenses and other current liabilities	0.6	0.6
Pension and post-retirement benefits	13.6	21.4
Accumulated Other Comprehensive Loss
Net actuarial loss	(2.8)	(6.9)
Prior service costs	0.0	0.0
Domestic | Post-retirement Medical Benefits
Balance Sheet
Accrued expenses and other current liabilities	0.5	0.6
Pension and post-retirement benefits	8.0	8.6
Accumulated Other Comprehensive Loss
Net actuarial loss	(0.1)	(0.6)
Prior service costs	0.0	0.0
Foreign | Pension and SERP Benefits
Balance Sheet
Accrued expenses and other current liabilities	0.9	0.8
Pension and post-retirement benefits	20.6	19.8
Accumulated Other Comprehensive Loss
Net actuarial loss	(2.3)	(2.1)
Prior service costs	0.0	0.0
Foreign | Post-retirement Medical Benefits
Balance Sheet
Accrued expenses and other current liabilities	0.0	0.0
Pension and post-retirement benefits	0.1	0.1
Accumulated Other Comprehensive Loss
Net actuarial loss	(0.6)	(0.7)
Prior service costs	$ 1.0	$ 1.4