Retirement Plans - Fair Value of Pension Assets (Details) - Pensions - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	$ 31.8	$ 31.2	$ 26.8
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	31.8	31.2
Fair Value, Measurements, Recurring | Cash and short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	0.2	0.1
Fair Value, Measurements, Recurring | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	9.2	8.1
Fair Value, Measurements, Recurring | Pooled funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	20.3	21.4
Fair Value, Measurements, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	2.1	1.6
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	9.4	8.2
Fair Value, Measurements, Recurring | Level 1 | Cash and short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	0.2	0.1
Fair Value, Measurements, Recurring | Level 1 | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	9.2	8.1
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	2.1	1.6
Fair Value, Measurements, Recurring | Level 2 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	2.1	1.6
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	0.0	0.0
Fair Value, Measurements, Recurring | Investments Measured at Net Asset Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	20.3	21.4
Fair Value, Measurements, Recurring | Investments Measured at Net Asset Value | Pooled funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension and other postretirement benefit asset	$ 20.3	$ 21.4