Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING ACTIVITIES:
Net income	$ 33,987	$ 17,168
Loss from discontinued operations, net of income taxes		(3,380)
Income from continuing operations	33,987	20,548
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization	9,451	8,905
Deferred income taxes	11,310	7,074
(Gain) loss on sale of assets	(145)	279
Amortization of deferred financing fees	403	868
Share-based compensation expense	1,675	2,000
Changes in assets and liabilities:
Accounts receivable	(24,229)	30,285
Contract revenues in excess of billings	(14,520)	1,538
Inventories	(2,215)	280
Prepaid expenses and other current assets	8,036	(1,678)
Accounts payable and accrued expenses	(523)	(935)
Billings in excess of contract revenues	6,062	36,062
Other noncurrent assets and liabilities	779	566
Net cash flows provided by operating activities from continuing operations	30,071	105,792
Net cash flows provided by operating activities of discontinued operations		2,668
Cash provided by operating activities	30,071	108,460
INVESTING ACTIVITIES:
Purchases of property and equipment	(8,733)	(7,704)
Proceeds from dispositions of property and equipment	447	147
Net cash flows used in investing activities of continuing operations	(8,286)	(7,557)
Net cash flows used in investing activities of discontinued operations		(60)
Cash used in investing activities	(8,286)	(7,617)
FINANCING ACTIVITIES:
Taxes paid on settlement of vested share awards	(1,928)	(2,188)
Exercise of options and purchases from employee stock plans	622	1,626
Repayments of revolving loans		(11,500)
Net cash flows used in financing activities of continuing operations	(1,306)	(12,062)
Net cash flows used in financing activities of discontinued operations		(253)
Cash used in financing activities	(1,306)	(12,315)
Net increase in cash, cash equivalents and restricted cash	20,479	88,528
Cash, cash equivalents and restricted cash at beginning of period	186,995	34,458
Cash, cash equivalents and restricted cash at end of period	207,474	122,986
Supplemental Cash Flow Information
Cash paid (received) for interest	(277)	229
Cash paid (refunded) for income taxes	137	(10)
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	$ 4,801	$ 6,239