CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 143,348	$ 150,139	$ 114,324
Adjustments to reconcile net income to net cash provided by operating activities-
Amortization of identifiable intangible assets	40,505	32,698	27,082
Depreciation expense	28,439	27,931	24,490
Change in right-of-use assets	17,592	16,692	16,887
Bad debt expense (benefit)	(1,452)	5,253	2,978
Deferred tax provision (benefit)	6,902	(7,953)	(4,251)
Amortization of debt financing costs	538	544	387
Gain on sale of assets	(1,540)	(1,445)	(1,701)
Changes in the fair value of contingent earn-out obligations	(7,820)	(9,119)	2,991
Stock-based compensation	10,593	6,934	5,878
(Increase) decrease in-
Receivables, net	(58,046)	38,486	(49,508)
Inventories	(5,651)	(1,457)	2,366
Prepaid expenses and other current assets	(8,623)	(4,855)	(15,519)
Costs and estimated earnings in excess of billings and unbilled accounts receivable	(17,271)	2,706	(4,312)
Other noncurrent assets	(1,174)	(1,373)	(735)
Increase (decrease) in-
Accounts payable and accrued liabilities	4,004	11,087	31,046
Billings in excess of costs and estimated earnings	44,620	19,434	4,376
Other long-term liabilities	(14,813)	808	(14,751)
Net cash provided by operating activities	180,151	286,510	142,028
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(22,330)	(24,131)	(31,750)
Proceeds from sales of property and equipment	3,101	2,270	2,159
Proceeds from sale of business			1,611
Cash paid for acquisitions, net of cash acquired	(227,493)	(185,941)	(196,470)
Net cash used in investing activities	(246,722)	(207,802)	(224,450)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility	275,000	268,000	356,000
Payments on revolving credit facility	(125,000)	(226,000)	(228,000)
Payments on term loan	(15,000)	(15,000)
Payments on other debt	(15,696)	(46,534)	(3,784)
Payments on finance lease liabilities	(3,805)
Debt financing costs			(1,405)
Payments of dividends to stockholders	(17,384)	(15,499)	(14,543)
Share repurchase	(27,054)	(30,120)	(19,550)
Shares received in lieu of tax withholding	(2,363)	(1,076)	(1,498)
Proceeds from exercise of options	5,634	2,144	2,350
Deferred acquisition payments	(400)	(650)	(637)
Payments for contingent consideration arrangements	(3,481)	(9,865)	(1,343)
Net cash provided by (used in) financing activities	70,451	(74,600)	87,590
NET INCREASE IN CASH AND CASH EQUIVALENTS	3,880	4,108	5,168
CASH AND CASH EQUIVALENTS, beginning of period	54,896	50,788	45,620
CASH AND CASH EQUIVALENTS, end of period	$ 58,776	$ 54,896	$ 50,788