Postretirement Benefit Plans - Amount Recognized in Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 9.1	$ 58.4
Prior service cost (benefit)	(24.3)	(21.7)
Total	(15.2)	36.7
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	5.7	30.0
Prior service cost (benefit)	0.3	0.3
Total	6.0	30.3
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	3.4	28.4
Prior service cost (benefit)	(24.6)	(22.0)
Total	$ (21.2)	$ 6.4