CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 53,042	$ 12,959
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	43,064	46,430
Amortization of intangible assets	6,184	5,015
Goodwill and intangible asset impairment	477	2,716
Stock-based compensation expense	911	1,169
Unrealized gain on short-term investments	(5,980)
Gain on sale of property and equipment	(3,880)	(3,361)
Changes in assets and liabilities:
Customer retention deposits	(445)	(451)
Accounts receivable	41,870	27,093
Costs and estimated earnings in excess of billings	(38,464)	(39,936)
Other current assets	17,210	13,865
Other long-term assets	(2,745)	(1,963)
Accounts payable	(17,813)	10,036
Billings in excess of costs and estimated earnings	46,067	(41,584)
Accrued expenses and other current liabilities	17,858	18,580
Other long-term liabilities	4,076	49
Net cash provided by operating activities	161,432	50,617
Cash flows from investing activities:
Purchase of property and equipment	(57,346)	(52,137)
Proceeds from sale of property and equipment	7,027	7,763
Purchase of short-term investments	(13,588)
Sale of short-term investments	350
Cash paid for acquisitions	(66,205)	(4,108)
Net cash used in investing activities	(129,762)	(48,482)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	30,000	30,000
Repayment of capital leases	(191)	(626)
Repayment of long-term debt	(41,088)	(36,867)
Payment of debt issuance costs for amended and restated credit agreement	(631)
Proceeds from issuance of common stock purchased under a long-term incentive plan	1,148	1,439
Repurchase of common stock	(4,999)
Dividends paid	(8,497)	(8,536)
Net cash used in financing activities	(24,258)	(14,590)
Net change in cash and cash equivalents	7,412	(12,455)
Cash and cash equivalents at beginning of the period	135,823	161,122
Cash and cash equivalents at end of the period	143,235	148,667
Cash paid:
Interest	6,236	6,654
Income taxes, net of refunds received	25,618	2,079
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES
Obligations incurred for the acquisition of property	4,163
Dividends declared and not yet paid	$ 2,829	$ 2,848