Multiemployer Plans Zones (Details 18)	12 Months Ended
	Dec. 31, 2020
Maximum
Multiemployer Plans [Line Items]
Multiemployer plan red zone status funded percentage	65.00%
Mulitiemployer plan yellow status funded percentage	80.00%
Minimum
Multiemployer Plans [Line Items]
Multiemployer plan yellow zone status funded percentage	65.00%
Multiemployer plan green zone status funded percentage	80.00%