Pension and Postretirement Plans - Schedule of Pension and Postretirement Costs (Benefits) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Other components of pension and postretirement benefit plans expense:
Interest cost on projected benefit obligation	3.8	3.7	7.7	7.5
Expected return on plan assets	(7.1)	(7.2)	(14.3)	(14.7)
Amortization of:
Prior service benefit	0.0	0.0	0.0	0.0
Actuarial loss	0.0	5.2	0.0	11.5
Pension / postretirement (benefit) cost	(3.3)	1.7	(6.6)	4.3
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0.1	0.1	0.2	0.2
Other components of pension and postretirement benefit plans expense:
Interest cost on projected benefit obligation	0.7	0.7	1.4	1.3
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of:
Prior service benefit	0.0	(0.7)	0.0	(1.3)
Actuarial loss	0.0	0.0	0.0	0.0
Pension / postretirement (benefit) cost	$ 0.8	$ 0.1	$ 1.6	$ 0.2