CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Cash and cash equivalents	$ 193,581	$ 233,711	$ 169,501
Contract assets	178,663	0	0
Costs and estimated earnings in excess of billings	0	103,965	90,112
Other current assets	43,125	36,513	54,542
Property and equipment, net	409,708	407,418	412,490
Accounts payable	226,253	237,673	170,006
Contract liabilities	71,030	0	0
Billings in excess of costs and estimated earnings	0	135,146	91,527
Accrued expenses and other current liabilities	$ 233,637	$ 236,407	$ 224,850
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	3,000,000	3,000,000	3,000,000
Preferred Stock, Shares Outstanding	0	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01
Common Stock, Shares Authorized	150,000,000	150,000,000	150,000,000
Common Stock, Shares, Issued	40,047,187	39,871,314	39,815,232
Common Stock, Shares, Outstanding	40,047,187	39,871,314	39,815,232
Consolidated Construction Joint Venture | Joint Venture Consolidated
Cash and cash equivalents	$ 91,903	$ 94,359	$ 60,406
Receivables, Net	17,598	52,031	55,215
Contract assets	23,889	0	0
Costs and estimated earnings in excess of billings	0	1,437	2,965
Other current assets	14,180	10,384	7,047
Property and equipment, net	44,655	38,361	26,161
Accounts payable	31,854	34,795	19,386
Contract liabilities	33,760	0	0
Billings in excess of costs and estimated earnings	0	37,701	34,467
Accrued expenses and other current liabilities	$ 2,090	$ 2,126	$ 1,426