Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities
Net loss	$ (171,868)	$ (36,641)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	84,713	92,700
Amortization related to the 2.75% Convertible Notes (See Note 14)	6,458	0
Gain on sales of property and equipment, net	(4,870)	(13,936)
Deferred income taxes	996	(2,150)
Stock-based compensation	5,203	8,924
Equity in net loss from unconsolidated joint ventures	38,529	93,274
Net income from affiliates	(4,415)	(10,159)
Non-cash impairment charges (See Note 4)	156,690	0
Other non-cash adjustments	2,071	4,630
Changes in assets and liabilities, net of the effect of an acquisition in 2019:
Receivables	(98,118)	(225,558)
Contract assets, net	144,558	(21,539)
Inventories	(13,226)	(6,178)
Contributions to unconsolidated construction joint ventures	(38,044)	(57,280)
Distributions from unconsolidated construction joint ventures and affiliates	9,279	13,181
Other assets, net	(6,208)	(10,390)
Accounts payable	(16,559)	143,678
Accrued expenses and other current liabilities, net	43,477	946
Net cash provided by (used in) operating activities	138,666	(26,498)
Investing activities
Purchases of marketable securities	(9,996)	0
Maturities of marketable securities	10,000	20,000
Proceeds from called marketable securities	24,996	0
Purchases of property and equipment	(74,901)	(83,329)
Proceeds from sales of property and equipment	12,283	28,104
Cash paid to purchase business	0	(6,227)
Other investing activities, net	(4,283)	(3,756)
Net cash used in investing activities	(41,901)	(45,208)
Financing activities
Proceeds from debt	50,000	105,574
Debt principal repayments	(6,321)	(86,018)
Cash dividends paid	(17,777)	(18,240)
Repurchases of common stock	(753)	(6,916)
Contributions from non-controlling partners	9,250	0
Distributions to non-controlling partners	(10,060)	(12,234)
Other financing activities, net	324	1,242
Net cash provided by (used in) financing activities	24,663	(16,592)
Net increase (decrease) in cash, cash equivalents and restricted cash	121,428	(88,298)
Cash, cash equivalents and restricted cash, beginning of period	268,108	278,629
Total cash, cash equivalents and restricted cash, end of period	389,536	190,331
Supplementary Information
Right of use assets obtained in exchange for lease obligations	9,486	19,005
Cash paid for operating lease liabilities	16,137	13,713
Cash paid during the period for:
Interest	11,966	13,758
Income taxes	2,360	11,900
Non-cash investing and financing activities:
RSUs issued, net of forfeitures	4,685	8,573
Accrued cash dividends	$ 5,935	$ 6,076