Defined Benefit and Postretirement Benefits Contributions by Plan Type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
DeferralofpensioncontributionsduetoCARESAct	$ 18.2
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	3.2	$ 21.4
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.5
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	2.5
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 1.0