Pension and Postretirement Plans - Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Sep. 07, 2021
Defined Benefit Plan Disclosure [Line Items]
Pension and postretirement benefit obligations (noncurrent liability)	$ 138.9	$ 141.1
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Total			$ 101.6
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued payroll and benefits (current liability)	1.5	2.0
Pension and postretirement benefit obligations (noncurrent liability)	47.4	50.7
Total	48.9	52.7
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Prior service (cost) benefit, net of tax of ($0.2)	0.0	0.0
Actuarial (loss) gain, net of tax of ($1.6), $0.7, $10.2, $0.1	(5.1)	2.0
Total	(5.1)	2.0
Actuarial gain (loss), tax	(1.6)	0.7
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued payroll and benefits (current liability)	8.1	7.8
Pension and postretirement benefit obligations (noncurrent liability)	91.1	89.8
Total	99.2	97.6
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Prior service (cost) benefit, net of tax of ($0.2)	(0.6)	0.0
Actuarial (loss) gain, net of tax of ($1.6), $0.7, $10.2, $0.1	32.8	0.6
Total	32.2	0.6
Prior service costs, tax	(0.2)
Actuarial gain (loss), tax	$ 10.2	$ 0.1