Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash and cash equivalents	$ 452,928	$ 436,136	$ 242,604
Receivables, net	475,160	540,812	477,718
Contract assets	185,220	164,939	226,518
Other current assets	64,286	42,199	60,001
Property and equipment, net	528,173	527,016	534,958
Accounts payable	306,834	359,160	312,105
Contract liabilities	160,149	171,321	133,811
Accrued expenses and other current liabilities	$ 524,452	$ 404,497	$ 355,393
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)	45,791,712	45,668,541	45,592,292
Common stock, shares outstanding (in shares)	45,791,712	45,668,541	45,592,292
Consolidated Construction Corporate Joint Venture [Member]
Cash and cash equivalents	$ 110,486	$ 74,819	$ 101,698
Receivables, net	32,539	56,147	28,320
Contract assets	37,683	33,838	17,584
Other current assets	12,298	13,252	16,078
Property and equipment, net	22,457	23,704	30,047
Accounts payable	52,217	53,033	58,475
Contract liabilities	70,968	79,777	47,509
Accrued expenses and other current liabilities	$ 4,640	$ 4,410	$ 2,458