Goodwill and Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Total Intangible Assets [Abstract]
Cost	$ 387,040	$ 387,040
Accumulated Amortization	(150,858)	(118,703)
Accumulated Impairment Charge	(113,067)	(113,067)
Carrying Value	123,115	155,270
Trade Names
Finite-Lived intangible assets
Cost	74,350	74,350
Accumulated Amortization	(23,754)	(21,267)
Accumulated Impairment Charge	(23,232)	(23,232)
Carrying Value	$ 27,364	$ 29,851
Weighted-Average Amortization Period	20 years	20 years
Customer relationships
Finite-Lived intangible assets
Cost	$ 39,800	$ 39,800
Accumulated Amortization	(22,103)	(21,048)
Accumulated Impairment Charge	(16,645)	(16,645)
Carrying Value	$ 1,052	$ 2,107
Weighted-Average Amortization Period	12 years	12 years
Construction contract backlog
Finite-Lived intangible assets
Cost	$ 149,290	$ 149,290
Accumulated Amortization	(105,001)	(76,388)
Carrying Value	$ 44,289	$ 72,902
Weighted-Average Amortization Period	3 years	3 years
Trade Names
Indefinite-lived intangible assets
Cost	$ 117,600	$ 117,600
Accumulated Impairment Charge	(67,190)	(67,190)
Carrying Value	50,410	50,410
Contractor license
Indefinite-lived intangible assets
Cost	6,000	6,000
Accumulated Impairment Charge	$ (6,000)	$ (6,000)