CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 174,340	$ 192,868
Accounts receivable	1,236,818	1,265,717
Retainage receivable	530,897	535,939
Other current assets	132,298	89,316
Accumulated depreciation	328,443	359,188
PROPERTY AND EQUIPMENT, net of accumulated depreciation	473,178	467,499
Accounts payable	659,290	699,971
Billings in excess of cost and estimated earnings	508,616	456,869
Unamortized discounts and debt issuance costs	$ 43,064	$ 45,631
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares issued	0	0
Common stock, shares authorized	75,000,000	75,000,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares issued	49,913,003	49,781,010
Common stock, shares outstanding	49,913,003	49,781,010
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	$ 52,871	$ 53,067
Accounts receivable	28,076	30,003
Retainage receivable	18,627	12,410
Other current assets	30,093	0
PROPERTY AND EQUIPMENT, net of accumulated depreciation	25,072	11,641
Accounts payable	9,183	19,243
Billings in excess of cost and estimated earnings	$ 199,618	$ 120,952