Goodwill and Intangible Assets (Schedule of Finite-Lived Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived intangible assets
Cost	$ 311,456	$ 311,456
Accumulated Amortization	(115,135)	(112,478)
Accumulated Impairment Charge	(113,067)	(113,067)
Carrying Value	83,254	85,911
Trade Names [Member]
Finite-Lived intangible assets
Cost	74,350	74,350
Accumulated Amortization	(20,645)	(18,780)
Accumulated Impairment Charge	(23,232)	(23,232)
Carrying Value	$ 30,473	$ 32,338
Weighted Average Amortization Period	20 years	20 years
Customer Relationships [Member]
Finite-Lived intangible assets
Cost	$ 39,800	$ 39,800
Accumulated Amortization	(20,784)	(19,992)
Accumulated Impairment Charge	(16,645)	(16,645)
Carrying Value	$ 2,371	$ 3,163
Weighted Average Amortization Period	12 years	12 years
Construction Contract Backlog [Member]
Finite-Lived intangible assets
Cost	$ 73,706	$ 73,706
Accumulated Amortization	(73,706)	(73,706)
Accumulated Impairment Charge	0	0
Carrying Value	$ 0	$ 0