CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 14,551	$ 8,447
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	2,314	2,130
Amortization	7,391	9,448
Stock-based compensation expense	1,467	1,034
Amortization of debt issuance costs and discount	159	165
Deferred income tax benefit	(248)	(410)
Amortization and adjustment of deferred credit	(203)	0
Other	(32)	(252)
Changes in assets and liabilities:
Accounts receivable and unbilled, net	(17,760)	(2,292)
Prepaid expenses and other current assets	(214)	(247)
Accounts payable	699	(1,331)
Accrued expenses	5,268	(10,508)
Pre-funded study costs	0	(3,497)
Advanced billings	6,817	(5,246)
Other assets and liabilities, net	3,089	1,884
Net cash provided by (used in) operating activities	23,298	(675)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property and equipment expenditures	(3,951)	(4,374)
Other	23	16
Net cash used in investing activities	(3,928)	(4,358)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock option exercises	566	193
Payment of debt	(4,125)	(3,094)
Payments on revolving loan	(20,000)	0
Payment of deemed landlord liability	(451)	(404)
Net cash used in financing activities	(24,010)	(3,305)
EFFECT OF EXCHANGE RATES ON CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	400	540
DECREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(4,240)	(7,798)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — Beginning of period	26,492	37,407
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — End of period	$ 22,252	$ 29,609