CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 114,324	$ 112,903	$ 55,272
Adjustments to reconcile net income to net cash provided by operating activities-
Amortization of identifiable intangible assets	27,082	20,089	17,404
Depreciation expense	24,490	22,600	20,052
Change in right-of-use assets	16,887
Goodwill impairment			1,105
Bad debt expense	2,978	3,562	182
Deferred tax provision (benefit)	(4,251)	4,456	4,178
Amortization of debt financing costs	387	383	376
Gain on sale of assets	(1,701)	(945)	(670)
Changes in the fair value of contingent earn-out obligations	2,991	2,066	(3,715)
Stock-based compensation	5,878	7,161	6,377
(Increase) decrease in-
Receivables, net	(49,508)	(68,621)	(37,799)
Inventories	2,366	(1,538)	(584)
Prepaid expenses and other current assets	(15,519)	519	2,467
Costs and estimated earnings in excess of billings and unbilled accounts receivable	(4,312)	(14,444)	1,869
Other noncurrent assets	(735)	(114)	1,005
Increase (decrease) in-
Accounts payable and accrued liabilities	31,046	47,871	22,068
Billings in excess of costs and estimated earnings	4,376	16,786	13,265
Other long-term liabilities	(14,751)	(5,544)	11,238
Net cash provided by operating activities	142,028	147,190	114,090
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(31,750)	(27,268)	(35,467)
Proceeds from sales of property and equipment	2,159	1,698	1,359
Proceeds from sale of business	1,611
Cash paid for acquisitions, net of cash acquired	(196,470)	(70,140)	(94,860)
Net cash used in investing activities	(224,450)	(95,710)	(128,968)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit	356,000	124,000	177,000
Payments on revolving line of credit	(228,000)	(119,000)	(132,000)
Payments on other debt	(3,784)	(1,127)	(835)
Payments on capital lease obligations			(256)
Debt financing costs	(1,405)	(844)
Payments of dividends to stockholders	(14,543)	(12,268)	(10,987)
Share repurchase	(19,550)	(28,533)	(9,007)
Shares received in lieu of tax withholding	(1,498)	(1,540)	(1,419)
Proceeds from exercise of options	2,350	3,105	2,052
Deferred acquisition payments	(637)	(750)	(2,802)
Payments for contingent consideration arrangements	(1,343)	(5,445)	(2,400)
Net cash provided by (used in) financing activities	87,590	(42,402)	19,346
NET INCREASE IN CASH AND CASH EQUIVALENTS	5,168	9,078	4,468
CASH AND CASH EQUIVALENTS, beginning of period	45,620	36,542	32,074
CASH AND CASH EQUIVALENTS, end of period	$ 50,788	$ 45,620	$ 36,542