Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Cash and cash equivalents	$ 464,049,000	$ 436,136,000	$ 388,024,000
Receivables, net	684,822,000	540,812,000	661,948,000
Contract assets	204,046,000	164,939,000	159,939,000
Other current assets	39,749,000	42,199,000	48,300,000
Property and equipment, net	510,658,000	527,016,000	536,256,000
Accounts payable	397,152,000	359,160,000	385,259,000
Contract liabilities	195,267,000	171,321,000	189,430,000
Accrued expenses and other current liabilities	$ 499,214,000	$ 404,497,000	$ 391,651,000
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)	45,826,409	45,668,541	45,655,682
Common stock, shares outstanding (in shares)	45,826,409	45,668,541	45,655,682
Consolidated Construction Corporate Joint Venture [Member]
Cash and cash equivalents	$ 119,611,000	$ 74,819,000	$ 92,587,000
Receivables, net	42,530,000	56,147,000	32,028,000
Contract assets	42,792	33,838	27,528
Other current assets	9,954,000	13,252,000	13,634,000
Property and equipment, net	17,534	23,704	25,765
Accounts payable	62,547	53,033	50,503
Contract liabilities	56,914	79,777	73,426
Accrued expenses and other current liabilities	$ 5,238,000	$ 4,410,000	$ 4,553,000