CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 27,725	$ 37,151	$ 63,682
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	61,433	58,408	50,918
Amortization of intangible assets	6,597	6,793	7,504
Goodwill and intangible asset impairment	2,716	401
Stock-based compensation expense	1,627	1,050	934
Gain on sale of property and equipment	(4,677)	(2,116)	(1,895)
Income from non-consolidated entities			(5,264)
Net deferred tax liabilities (assets)	10,905	(7,004)	8,970
Changes in assets and liabilities:
Customer retention deposits	2,117	(2,117)	4,823
Accounts receivable	(65,806)	19,528	(29,659)
Costs and estimated earnings in excess of billings	(22,163)	(47,499)	(11,508)
Other current assets	17,665	4,949	(25,767)
Other long-term assets	(1,792)	189	72
Accounts payable	42,934	(5,086)	921
Billings in excess of costs and estimated earnings	(27,519)	(19,619)	(14,770)
Contingent earnout liabilities		(6,722)	(4,145)
Accrued expenses and other current liabilities	14,492	11,729	(7,354)
Other long-term liabilities	(3,677)	(1,658)	(1,361)
Net cash provided by operating activities	62,577	48,377	36,101
Cash flows from investing activities:
Purchase of property and equipment	(58,027)	(67,097)	(87,954)
Proceeds from sale of property and equipment	9,603	9,889	5,814
Purchase of short-term investments			(33,770)
Sale of short-term investments		30,992	21,464
Cash received for the sale of equity method investments			6,439
Cash paid for acquisitions	(10,997)	(22,302)	(14,596)
Net cash used in investing activities	(59,421)	(48,518)	(102,603)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	45,000	75,278	58,519
Repayment of capital leases	(793)	(1,336)	(3,276)
Repayment of long-term debt	(57,719)	(43,927)	(35,107)
Proceeds from issuance of common stock purchased by management under long-term incentive plan	1,440	1,621	1,671
Cash distribution to non-controlling interest holder		(29)	(1,590)
Repurchase of common stock	(4,999)		(2,844)
Dividends paid	(11,384)	(9,809)	(7,483)
Net cash provided by (used in) financing activities	(28,455)	21,798	9,890
Net change in cash and cash equivalents	(25,299)	21,657	(56,612)
Cash and cash equivalents at beginning of the period	161,122	139,465	196,077
Cash and cash equivalents at end of the period	135,823	161,122	139,465
Cash paid during the period for:
Interest	8,819	7,688	6,432
Income taxes, net of refunds received	8,624	18,696	57,613
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES
Obligations incurred for the acquisition of property and equipment		25
Dividends declared and not yet paid	$ 2,839	$ 2,842	$ 2,062