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 including noncontrolling interests	$ 64,896	$ 57,440	$ 28,599
Adjustments to reconcile net income to net cash provided by operating activities
Amortization of identifiable intangible assets	8,185	7,481	7,653
Depreciation expense	17,981	15,935	13,683
Goodwill impairment			727
Bad debt expense (benefit)	(27)	1,552	1,275
Deferred tax expense (benefit)	(1,239)	(414)	(4,579)
Amortization of debt financing costs	367	317	283
Gain on sale of assets	(761)	(880)	(830)
Changes in the fair value of contingent earn-out obligations	(731)	(225)	245
Stock-based compensation expense	5,041	5,609	4,806
(Increase) decrease in-
Receivables, net	7,038	(3,584)	(18,339)
Inventories	213	956	281
Prepaid expenses and other current assets	(8,850)	364	1,494
Costs and estimated earnings in excess of billings	3,144	(3,630)	2,744
Other noncurrent assets	(143)	(479)	(321)
Increase (decrease) in-
Accounts payable and accrued liabilities	2,736	11,617	(4,078)
Billings in excess of costs and estimated earnings	(8,351)	7,908	7,545
Other long-term liabilities	1,689	(2,100)	1,364
Net cash provided by operating activities	91,188	97,867	42,552
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(23,217)	(20,808)	(19,183)
Proceeds from sales of property and equipment	1,062	1,338	1,355
Cash paid for acquisitions, net of cash acquired	(57,163)	(6,158)	(56,314)
Net cash used in investing activities	(79,318)	(25,628)	(74,142)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit	144,000	24,500	128,500
Payments on revolving line of credit	(154,000)	(53,000)	(90,000)
Payments on other debt	592		2,000
Payments on capital lease obligations	(251)	(443)	(115)
Debt financing costs	(789)		(568)
Payments of dividends to shareholders	(10,264)	(9,358)	(8,444)
Share repurchase	(13,088)	(8,330)	(7,974)
Shares received in lieu of tax withholding	(1,304)	(937)	(531)
Excess tax benefit of stock-based compensation		1,240	115
Proceeds from exercise of options	1,578	3,738	1,229
Distributions to noncontrolling interests		(4,904)	(8,612)
Deferred acquisition payments	(1,350)
Payments for contingent consideration arrangements	(200)	(345)
Net cash provided by (used in) financing activities	(36,260)	(47,839)	11,600
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(24,390)	24,400	(19,990)
CASH AND CASH EQUIVALENTS, beginning of period	56,464	32,064	52,054
CASH AND CASH EQUIVALENTS, end of period	$ 32,074	$ 56,464	$ 32,064