Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net (loss) income	$ (56,702)	$ 11,536	$ 42,457
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, depletion and amortization	123,418	111,544	66,345
Gain on sales of property and equipment, net	(18,703)	(4,910)	(4,182)
Change in deferred income taxes	(22,924)	12,110	(2,739)
Stock-based compensation	10,213	14,784	15,764
Equity in net loss from unconsolidated joint ventures	120,632	44,689	45,856
Net income from affiliates	(11,454)	(6,935)	(7,107)
Other non-cash adjustments	4,020	4,916	(939)
Changes in assets and liabilities, net of the effects of acquisitions in 2019 and 2018:
Receivables	(58,947)	(9,247)	(65,750)
Costs and estimated earnings in excess of billings, net	0	0	(21,607)
Contract assets, net	(40,084)	11,384	0
Inventories	380	(2,120)	(7,252)
Contributions to unconsolidated construction joint ventures	(83,765)	(104,333)	(16,937)
Distributions from unconsolidated construction joint ventures and affiliates	19,064	16,922	39,955
Other assets, net	(3,928)	21,619	13,586
Accounts payable	140,027	(21,456)	37,692
Accrued expenses and other current liabilities, net	(9,809)	(14,113)	11,053
Net cash provided by operating activities	111,438	86,390	146,195
Investing activities
Purchases of marketable securities	0	(9,952)	(124,543)
Maturities of marketable securities	30,000	75,000	120,000
Purchases of property and equipment	(106,828)	(111,101)	(67,695)
Proceeds from sales of property and equipment	37,091	16,238	10,202
Cash paid to purchase businesses, net of cash and restricted cash acquired	(6,227)	(55,027)	0
Proceeds from the sale of a business	0	47,812	0
Other investing activities, net	5,642	(2,568)	2,850
Net cash used in investing activities	(40,322)	(39,598)	(59,186)
Financing activities
Proceeds from issuance of debt	105,574	203,250	25,000
Proceeds from issuance of 2.75% Convertible Notes, net (See Note 15)	230,000	0	0
Proceeds from issuance of common stock warrants, net (See Note 15)	11,500	0	0
Purchase of Hedge Option, net (See Note 15)	(37,375)	0	0
Debt principal repayments	(313,150)	(153,924)	(45,000)
Cash dividends paid	(24,316)	(22,424)	(20,687)
Repurchases of common stock	(36,900)	(16,557)	(6,977)
Contributions from non-controlling partners	68	200	11,500
Distributions to non-controlling partners	(12,235)	(13,275)	(7,109)
Debt issuance costs	(6,507)	0	0
Other financing activities, net	1,704	856	649
Net cash used in financing activities	(81,637)	(1,874)	(42,624)
Net (decrease) increase in cash, cash equivalents and restricted cash	(10,521)	44,918	44,385
Cash, cash equivalents and restricted cash, beginning of period	278,629	233,711	189,326
Total cash, cash equivalents and restricted cash, end of period	268,108	278,629	233,711
Supplementary Information
Right of use assets obtained in exchange for lease obligations	25,360	0	0
Cash paid for operating lease liabilities	18,660	0	0
Cash paid during the period for:
Interest	17,322	14,864	11,446
Income taxes	11,898	19,069	33,948
Other non-cash operating activities:
Performance guarantees	(6,284)	0	5,497
Non-cash investing and financing activities:
Reclassification of the equity portion of the 2.75% Convertible Notes from debt to equity (See Note 15)	37,375
RSUs issued, net of forfeitures (See Note 18)	8,596	13,728	11,505
Accrued cash dividends	5,915	6,068	5,183
Common stock issued in acquisition	0	321,019	0
Common stock issued in conversion of 8.0% Convertible Notes	0	53,086	0
Premium on 8.0% Convertible Notes	$ 0	$ 30,702	$ 0