Employee Retirement Plans and Postretirement Benefits Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans, Plan Contributions	$ 8.2	$ 7.9	$ 7.9
Prescription Drug Benefit, Amount Paid	$ 33.0	$ 37.6	$ 37.1