Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenues	$ 448,885	$ 416,833	$ 906,771	$ 827,999
Operating expenses:
Direct salaries and related costs	292,086	268,433	591,563	535,378
General and administrative	110,924	102,664	220,551	205,911
Depreciation, net	12,809	12,630	25,924	25,091
Amortization of intangibles	2,959	4,093	5,946	8,212
Impairment of long-lived assets	386	1,800	1,536	1,800
Total operating expenses	419,164	389,620	845,520	776,392
Income from operations	29,721	27,213	61,251	51,607
Other income (expense):
Interest income	103	165	201	428
Interest (expense)	(382)	(560)	(805)	(1,280)
Other income (expense), net	92	1,797	(230)	(2,996)
Total other income (expense), net	(187)	1,402	(834)	(3,848)
Income before income taxes	29,534	28,615	60,417	47,759
Income taxes	6,354	6,385	12,259	11,611
Net income	$ 23,180	$ 22,230	$ 48,158	$ 36,148
Net income per common share:
Basic	$ 0.58	$ 0.55	$ 1.21	$ 0.89
Diluted	$ 0.58	$ 0.55	$ 1.21	$ 0.88
Weighted average common shares outstanding:
Basic	39,779	40,318	39,711	40,726
Diluted	39,942	40,380	39,951	40,857