CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 594,536	$ 480,851	$ 1,594,520	$ 1,326,850
COST OF SERVICES	466,668	379,993	1,266,416	1,054,300
Gross profit	127,868	100,858	328,104	272,550
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	75,297	66,707	216,528	196,553
GOODWILL IMPAIRMENT				1,105
GAIN ON SALE OF ASSETS	(219)	(184)	(630)	(464)
Operating income	52,790	34,335	112,206	75,356
OTHER INCOME (EXPENSE):
Interest income	25	16	53	55
Interest expense	(1,152)	(961)	(2,601)	(2,392)
Changes in the fair value of contingent earn-out obligations	434	2,469	493	1,845
Other	39	10	4,062	57
Other income (expense)	(654)	1,534	2,007	(435)
INCOME BEFORE INCOME TAXES	52,136	35,869	114,213	74,921
PROVISION FOR INCOME TAXES	13,595	13,585	26,466	27,188
NET INCOME	$ 38,541	$ 22,284	$ 87,747	$ 47,733
INCOME PER SHARE:
Basic (in shares)	$ 1.03	$ 0.60	$ 2.36	$ 1.28
Diluted (in shares)	$ 1.02	$ 0.59	$ 2.33	$ 1.27
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic (in shares)	37,294	37,232	37,236	37,259
Diluted (in shares)	37,667	37,626	37,634	37,684
DIVIDENDS PER SHARE (in dollars per share)	$ 0.085	$ 0.075	$ 0.240	$ 0.220