Employee Benefit Plans - Fair Values of Pension Plan Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / item	Dec. 31, 2020 USD ($)
Employee benefit plans
Fair value of plan assets	$ 454.0	$ 478.1
Fixed income common trust funds
Employee benefit plans
Fair value of plan assets	291.2	315.4
Non-U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.3	0.3
U.S. Government securities
Employee benefit plans
Fair value of plan assets	25.8	25.2
Global equity common trust funds
Employee benefit plans
Fair value of plan assets	58.0	32.1
Commingled global fund allocation
Employee benefit plans
Fair value of plan assets	67.4	81.7
Short-term investments
Employee benefit plans
Fair value of plan assets	$ 10.4	22.5
Value of short-term investments (in dollars per unit) | $ / item	1.00
Other
Employee benefit plans
Fair value of plan assets	$ 0.9	0.9
Quoted Prices in Active Markets for Identical Assets (Level 1)
Employee benefit plans
Fair value of plan assets	10.4	22.5
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed income common trust funds
Employee benefit plans
Fair value of plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Global equity common trust funds
Employee benefit plans
Fair value of plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commingled global fund allocation
Employee benefit plans
Fair value of plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
Employee benefit plans
Fair value of plan assets	10.4	22.5
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Observable Inputs (Level 2)
Employee benefit plans
Fair value of plan assets	442.7	454.7
Significant Observable Inputs (Level 2) | Fixed income common trust funds
Employee benefit plans
Fair value of plan assets	291.2	315.4
Significant Observable Inputs (Level 2) | Non-U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.3	0.3
Significant Observable Inputs (Level 2) | U.S. Government securities
Employee benefit plans
Fair value of plan assets	25.8	25.2
Significant Observable Inputs (Level 2) | Global equity common trust funds
Employee benefit plans
Fair value of plan assets	58.0	32.1
Significant Observable Inputs (Level 2) | Commingled global fund allocation
Employee benefit plans
Fair value of plan assets	67.4	81.7
Significant Observable Inputs (Level 2) | Short-term investments
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Observable Inputs (Level 2) | Other
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3)
Employee benefit plans
Fair value of plan assets	0.9	0.9
Significant Unobservable Inputs (Level 3) | Fixed income common trust funds
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Non-U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | U.S. Government securities
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Global equity common trust funds
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Commingled global fund allocation
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Short-term investments
Employee benefit plans
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Other
Employee benefit plans
Fair value of plan assets	$ 0.9	$ 0.9