CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 19,198	$ 14,551
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	1,991	2,314
Amortization	5,844	7,391
Stock-based compensation expense	3,183	1,467
Amortization of debt issuance costs and discount	138	159
Noncash lease expense	2,363	0
Deferred income tax provision (benefit)	656	(248)
Amortization and adjustment of deferred credit	(200)	(203)
Other	(43)	(32)
Changes in assets and liabilities:
Accounts receivable and unbilled, net	4,255	(17,760)
Prepaid expenses and other current assets	(1,642)	(214)
Accounts payable	(2,684)	699
Accrued expenses	(5,221)	5,268
Advanced billings	2,437	6,817
Lease liabilities	(2,041)	0
Other assets and liabilities, net	5,771	3,089
Net cash provided by operating activities	34,005	23,298
CASH FLOWS FROM INVESTING ACTIVITIES:
Property and equipment expenditures	(2,520)	(3,951)
Other	(1,322)	23
Net cash used in investing activities	(3,842)	(3,928)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock option exercises	972	566
Payment of debt	(24,000)	(4,125)
Payments on revolving loan	0	(20,000)
Payment of deemed landlord liability	0	(451)
Net cash used in financing activities	(23,028)	(24,010)
EFFECT OF EXCHANGE RATES ON CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(290)	400
INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	6,845	(4,240)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — Beginning of period	23,282	26,492
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — End of period	$ 30,127	$ 22,252