Pension and Postretirement Plans - Schedule of Pension and Postretirement Costs (Benefits) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0.0	$ 0.0
Other components of pension and postretirement benefit plans expense:
Interest cost on projected benefit obligation	3.9	3.8
Expected return on plan assets	(7.2)	(7.5)
Amortization of:
Prior service benefit	0.0	0.0
Actuarial loss	0.0	6.3
Pension / postretirement (benefit) cost	(3.3)	2.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0.1	0.1
Other components of pension and postretirement benefit plans expense:
Interest cost on projected benefit obligation	0.7	0.6
Expected return on plan assets	0.0	0.0
Amortization of:
Prior service benefit	0.0	(0.6)
Actuarial loss	0.0	0.0
Pension / postretirement (benefit) cost	$ 0.8	$ 0.1