CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenue, net (includes $5.1 million and $1.5 million with related parties for the three months ended March 31, 2019 and 2018, respectively)	$ 200,741	$ 163,077
Operating expenses:
Direct service costs, excluding depreciation and amortization	75,109	60,341
Reimbursed out-of-pocket expenses	70,594	56,913
Total direct costs	145,703	117,254
Selling, general and administrative	21,308	15,999
Depreciation	1,991	2,314
Amortization	5,844	7,391
Total operating expenses	174,846	142,958
Income from operations	25,895	20,119
Other expense, net:
Miscellaneous expense, net	(282)	(153)
Interest expense, net	(955)	(2,309)
Total other expense, net	(1,237)	(2,462)
Income before income taxes	24,658	17,657
Income tax provision	5,460	3,106
Net income	$ 19,198	$ 14,551
Net income per share attributable to common shareholders:
Basic	$ 0.54	$ 0.41
Diluted	$ 0.51	$ 0.40
Weighted average common shares outstanding:
Basic	35,698	35,486
Diluted	37,285	36,449