CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 318,720	$ 374,289
Accounts receivable	1,368,892	1,415,063
Retainage receivable	661,382	648,441
Costs and estimated earnings in excess of billings	1,255,992	1,236,734
Other current assets	236,943	249,455
Accumulated depreciation	452,904	434,294
Property and equipment, net	478,338	489,217
Unamortized discount and debt issuance costs, current	941	2,040
Accounts payable	716,326	794,611
Retainage payable	318,692	315,135
Billings in excess of costs and estimated earnings	818,757	839,222
Accrued expenses and other current liabilities	176,264	215,207
Unamortized discount and debt issuance costs, non-current	$ 19,478	$ 20,209
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares issued (in shares)	0	0
Common stock, shares authorized (in shares)	112,500,000	112,500,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares issued (in shares)	50,937,607	50,827,205
Common stock, shares outstanding (in shares)	50,937,607	50,827,205
VIEs
Cash and cash equivalents	$ 91,768	$ 105,735
Accounts receivable	78,924	86,012
Retainage receivable	129,050	122,335
Costs and estimated earnings in excess of billings	55,315	39,846
Other current assets	49,182	51,746
Property and equipment, net	8,526	12,840
Accounts payable	81,694	116,461
Retainage payable	28,027	26,439
Billings in excess of costs and estimated earnings	332,704	362,427
Accrued expenses and other current liabilities	$ 6,838	$ 9,595