Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net (loss) income	$ (103,129)	$ 43,354
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	92,700	77,816
Gain on sales of property and equipment, net	(13,936)	(5,066)
Change in deferred income taxes	(37,338)	(2,207)
Stock-based compensation	8,924	12,621
Equity in net loss from unconsolidated joint ventures	173,008	16,343
Net income from affiliates	(10,159)	(5,527)
Other non-cash adjustments	4,630	0
Changes in assets and liabilities, net of the effects of acquisitions:
Receivables	(224,475)	(154,996)
Contract assets, net	(13,276)	355
Inventories	(6,178)	(4,283)
Contributions to unconsolidated construction joint ventures	(57,280)	(89,000)
Distributions from unconsolidated construction joint ventures and affiliates	13,181	30,014
Other assets, net	(1,141)	16,295
Accounts payable	148,739	41,672
Accrued expenses and other current liabilities, net	(768)	37,352
Net cash (used in) provided by operating activities	(26,498)	14,743
Investing activities
Purchases of marketable securities	0	(9,952)
Maturities of marketable securities	20,000	60,000
Purchases of property and equipment	(83,329)	(86,131)
Proceeds from sales of property and equipment	28,104	9,480
Cash paid to purchase businesses, net of cash and restricted cash acquired	(6,227)	(55,030)
Other investing activities, net	(3,756)	320
Net cash used in investing activities	(45,208)	(81,313)
Financing activities
Proceeds from debt	105,574	143,250
Debt principal repayments	(86,018)	(42,149)
Cash dividends paid	(18,240)	(16,328)
Repurchases of common stock	(6,916)	(6,369)
Distributions to non-controlling partners, net	(12,234)	(10,128)
Other financing activities, net	1,242	441
Net cash (used in) provided by financing activities	(16,592)	68,717
Net (decrease) increase in cash, cash equivalents and restricted cash	(88,298)	2,147
Cash, cash equivalents and $5,825 and $0 in restricted cash at beginning of each period	278,629	233,711
Cash, cash equivalents and $5,658 and $5,599 in restricted cash at end of each period	190,331	235,858
Supplementary Information
Right of use assets obtained in exchange for lease obligations	19,005	0
Cash paid for operating lease liabilities	13,713	0
Cash paid during the period for:
Interest	13,758	9,029
Income taxes	11,900	8,576
Other non-cash operating activities:
Performance guarantees	(6,284)	0
Non-cash investing and financing activities:
Common stock issued in acquisition	0	321,075
Common stock issued in conversion of 8% Convertible Notes	0	53,086
Premium on 8.0% Convertible Notes	0	30,702
RSUs issued, net of forfeitures	8,573	13,537
Accrued cash dividends	6,076	6,097
Accrued equipment purchases	$ 674	$ 4,783