CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 833,896	$ 714,099	$ 2,217,552	$ 2,157,698
COST OF SERVICES	674,684	566,903	1,808,416	1,747,714
Gross profit	159,212	147,196	409,136	409,984
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	95,287	90,888	271,050	268,857
GAIN ON SALE OF ASSETS	(180)	(377)	(1,021)	(1,243)
Operating income	64,105	56,685	139,107	142,370
OTHER INCOME (EXPENSE):
Interest income	1	7	7	99
Interest expense	(1,586)	(1,733)	(4,443)	(6,904)
Changes in the fair value of contingent earn-out obligations	(1,244)	3,423	4,523	1,824
Other	20	(15)	112	10
Other income (expense)	(2,809)	1,682	199	(4,971)
INCOME BEFORE INCOME TAXES	61,296	58,367	139,306	137,399
PROVISION FOR INCOME TAXES	14,999	8,279	33,553	30,100
NET INCOME	$ 46,297	$ 50,088	$ 105,753	$ 107,299
INCOME PER SHARE:
Basic	$ 1.28	$ 1.37	$ 2.91	$ 2.93
Diluted	$ 1.27	$ 1.36	$ 2.90	$ 2.92
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic	36,296	36,557	36,328	36,604
Diluted	36,434	36,750	36,500	36,797