Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Sep. 30, 2020	Jun. 30, 2021
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer		$ 2.1
Defined Benefit Plan Effect Of Settlements And Curtailments On Accumulated Benefit Obligation	$ 22.7
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year		6.0
Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer		0.1
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year		$ 1.0
Defined benefit plan settlement [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer	$ 1.8