Defined Benefit and Postretirement Benefits Contributions by Plan Type (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 20.7
Defined Benefit Plan, Plan Assets, Contributions by Employer	15.7
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	2.6
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0.1