Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Cash and cash equivalents	$ 288,922	$ 262,273	$ 144,958
Receivables, net	596,922	547,417	564,543
Contract assets	191,919	211,441	224,389
Other current assets	57,614	46,016	80,560
Property and equipment, net	540,053	542,297	558,378
Accounts payable	358,401	400,775	302,651
Contract liabilities	159,818	95,737	128,443
Accrued expenses and other current liabilities	$ 363,128	$ 337,300	$ 360,231
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)	45,651,914	45,503,805	46,838,199
Common stock, shares outstanding (in shares)	45,651,914	45,503,805	46,838,199
Consolidated Construction Corporate Joint Venture [Member]
Cash and cash equivalents	$ 93,500	$ 78,132	$ 115,933
Receivables, net	31,978	29,564	31,656
Contract assets	26,075	25,034	17,371
Other current assets	14,392	13,350	11,440
Property and equipment, net	27,256	31,136	31,560
Accounts payable	56,315	57,795	50,338
Contract liabilities	69,688	20,994	28,702
Accrued expenses and other current liabilities	$ 4,179	$ 2,415	$ 4,311