CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 272,804	$ 233,711
Receivables, Net	473,246	479,791
Contract assets	219,754	0
Costs and estimated earnings in excess of billings	0	103,965
Other current assets	48,731	36,513
Property and equipment, net	549,688	407,418
Accounts payable	251,481	237,673
Contract liabilities	105,449	0
Billings in excess of costs and estimated earnings	0	135,146
Accrued expenses and other current liabilities	$ 273,626	$ 236,407
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	3,000,000	3,000,000
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	150,000,000	150,000,000
Common Stock, Shares, Issued	46,665,889	39,871,314
Common Stock, Shares, Outstanding	46,665,889	39,871,314
Consolidated Construction Joint Venture [Member] | Joint Venture Consolidated [Member]
Cash and cash equivalents	$ 131,965	$ 94,359
Receivables, Net	21,237	52,031
Contract assets	19,699	0
Costs and estimated earnings in excess of billings	0	1,437
Other current assets	11,744	10,384
Property and equipment, net	34,761	38,361
Accounts payable	37,086	34,795
Contract liabilities	60,288	0
Billings in excess of costs and estimated earnings	0	37,701
Accrued expenses and other current liabilities	$ 2,046	$ 2,126