CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (9,662)	$ (23,851)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	15,511	14,649
Gain on sales of property and equipment	(543)	(270)
Stock-based compensation	7,772	8,913
Equity in net income from unconsolidated joint ventures	(2,637)	(1,456)
Changes in assets and liabilities:
Receivables	58,527	68,272
Costs and estimated earnings in excess of billings, net	0	(25,581)
Contract assets, net	(47,777)	0
Inventories	(8,798)	(3,536)
Contributions to unconsolidated construction joint ventures	(26,067)	(813)
Distributions from unconsolidated construction joint ventures	4,036	16,179
Other assets, net	(6,136)	(18,465)
Accounts payable	(12,838)	(28,161)
Accrued expenses and other current liabilities, net	(9,008)	7,456
Net cash (used in) provided by operating activities	(37,620)	13,336
Investing activities
Purchases of marketable securities	(9,952)	(29,910)
Maturities of marketable securities	35,000	30,000
Purchases of property and equipment ($0 and $6,207 related to CCJVs)	(15,967)	(21,372)
Proceeds from sales of property and equipment	675	1,060
Other investing activities, net	345	67
Net cash provided by (used in) investing activities	10,101	(20,155)
Financing activities
Long-term debt principal repayments	(1,250)	(1,250)
Cash dividends paid	(5,183)	(5,151)
Repurchases of common stock	(6,119)	(6,448)
Other financing activities, net	(59)	(157)
Net cash used in financing activities	(12,611)	(13,006)
Decrease in cash and cash equivalents	(40,130)	(19,825)
Cash and cash equivalents at beginning of period	233,711	189,326
Cash and cash equivalents at end of period	193,581	169,501
Cash paid during the period for:
Interest	1,509	1,242
Income taxes	149	1,897
Non-cash investing and financing activities:
Restricted stock units issued, net of forfeitures	12,257	11,109
Accrued cash dividends	5,206	5,176
Accrued equipment purchases	(1,418)	749
Consolidated Construction Joint Venture | Joint Venture Consolidated
Investing activities
Purchases of property and equipment ($0 and $6,207 related to CCJVs)	0	6,207
Financing activities
Cash and cash equivalents at beginning of period	94,359
Cash and cash equivalents at end of period	$ 91,903	$ 60,406