CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue, net (includes $5.5 million and $5.1 million with related parties for the three months ended March 31, 2020 and 2019, respectively)	$ 230,879	$ 200,741
Operating expenses:
Direct service costs, excluding depreciation and amortization	88,795	75,109
Reimbursed out-of-pocket expenses	77,006	70,594
Total direct costs	165,801	145,703
Selling, general and administrative	25,124	21,308
Depreciation	2,453	1,991
Amortization	1,997	5,844
Total operating expenses	195,375	174,846
Income from operations	35,504	25,895
Other income (expense), net:
Miscellaneous income (expense), net	617	(282)
Interest income (expense), net	357	(955)
Total other income (expense), net	974	(1,237)
Income before income taxes	36,478	24,658
Income tax provision	7,524	5,460
Net income	$ 28,954	$ 19,198
Net income per share attributable to common shareholders:
Basic	$ 0.80	$ 0.54
Diluted	$ 0.76	$ 0.51
Weighted average common shares outstanding:
Basic	36,024	35,698
Diluted	38,030	37,285