Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES:
Net income (loss)	$ 25,414	$ (10,295)
Loss from discontinued operations, net of income taxes	(6,631)	(4,469)
Income (loss) from continuing operations	32,045	(5,826)
Adjustments to reconcile net income (loss) to net cash flows provided by operating activities:
Depreciation and amortization	18,001	26,838
Deferred income taxes	11,179	(4,434)
(Gain) loss on sale of assets	360	(1,256)
Other non-cash restructuring items		2,015
Amortization of deferred financing fees	1,941	1,769
Unrealized foreign currency gain		(201)
Share-based compensation expense	3,619	1,986
Changes in assets and liabilities:
Accounts receivable	14,012	(11,343)
Contract revenues in excess of billings	(13,207)	23,983
Inventories	(1,300)	1,083
Prepaid expenses and other current assets	870	11,604
Accounts payable and accrued expenses	10,044	(10,946)
Billings in excess of contract revenues	32,817	(3,091)
Other noncurrent assets and liabilities	1,404	(4,743)
Net cash flows provided by operating activities from continuing operations	111,785	27,438
Net cash flows used in operating activities of discontinued operations	(5,814)	(2,162)
Cash provided by operating activities	105,971	25,276
INVESTING ACTIVITIES:
Purchases of property and equipment	(24,316)	(11,754)
Proceeds from dispositions of property and equipment	5,516	9,930
Net cash flows used in investing activities of continuing operations	(18,800)	(1,824)
Net cash flows provided by investing activities of discontinued operations	17,198	13
Cash used in investing activities	(1,602)	(1,811)
FINANCING ACTIVITIES:
Deferred financing fees	(2,388)
Repayments of debt		(297)
Taxes paid on settlement of vested share awards	(2,929)	(1,060)
Exercise of options and purchases from employee stock plans	3,756	443
Borrowings under revolving loans		18,000
Repayments of revolving loans	(11,500)	(42,118)
Net cash flows used in financing activities of continuing operations	(13,061)	(25,032)
Net cash flows used in financing activities of discontinued operations	(191)	(773)
Cash used in financing activities	(13,252)	(25,805)
Effect of foreign currency exchange rates on cash and cash equivalents		26
Net increase (decrease) in cash, cash equivalents and restricted cash	91,117	(2,314)
Cash, cash equivalents and restricted cash at beginning of period	34,458	17,352
Cash, cash equivalents and restricted cash at end of period	125,575	15,038
Cash and cash equivalents	125,575	13,538
Restricted cash included in other long-term assets		1,500
Cash, cash equivalents and restricted cash at end of period	125,575	15,038
Supplemental Cash Flow Information
Cash paid for interest	12,963	16,245
Cash paid for income taxes	168	243
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	$ 7,760	5,220
Repayments of debt with proceeds from sale-leaseback transactions		$ 13,034