Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Cash and cash equivalents	$ 184,673	$ 272,804	$ 230,259
Receivables, net	700,387	473,246	618,070
Contract assets	233,925	219,754	213,989
Other current assets	42,698	48,731	95,173
Property and equipment, net	542,796	549,688	560,618
Accounts payable	399,528	251,481	316,917
Contract liabilities	106,010	105,449	117,759
Accrued expense and other current liabilities	$ 342,040	$ 273,626	$ 296,033
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	3,000,000	3,000,000	3,000,000
Preferred stock, outstanding (in shares)	0	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000	150,000,000
Common stock, shares issued (in shares)	46,741,263	46,665,889	46,897,092
Common stock, shares outstanding (in shares)	46,741,263	46,665,889	46,897,092
Consolidated Construction Corporate Joint Venture [Member]
Cash and cash equivalents	$ 77,870	$ 131,965	$ 125,165
Receivables, net	29,108	21,237	26,142
Contract assets	39,717	19,699	20,968
Other current assets	10,765	11,744	11,361
Property and equipment, net	27,752	34,761	36,061
Accounts payable	50,625	37,086	33,426
Contract liabilities	21,378	60,288	67,139
Accrued expense and other current liabilities	$ 4,193	$ 2,046	$ 1,975