Multiemployer Plan Contributions (Details 20) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Multiemployer Plans, Defined Contribution [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 54.2	$ 49.2	$ 31.1
Other Postretirement Benefits
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 63.8	$ 59.5	$ 51.9