CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 70,630	$ 50,424
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	6,035	6,883
Amortization	11,834	22,171
Stock-based compensation expense	18,034	4,386
Amortization of debt issuance costs and discount	954	471
Noncash lease expense	7,212	0
Deferred income tax provision	2,839	7,260
Amortization and adjustment of deferred credit	(601)	(7,515)
Other	1,768	487
Changes in assets and liabilities:
Accounts receivable and unbilled, net	(5,982)	(12,845)
Prepaid expenses and other current assets	(9,039)	(2,542)
Accounts payable	2,818	(1,323)
Accrued expenses	15,427	21,613
Advanced billings	21,901	28,277
Lease liabilities	(6,477)	0
Other assets and liabilities, net	7,574	(605)
Net cash provided by operating activities	144,927	117,142
CASH FLOWS FROM INVESTING ACTIVITIES:
Property and equipment expenditures	(12,152)	(12,575)
Other	(1,262)	(186)
Net cash used in investing activities	(13,414)	(12,761)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock option exercises	5,686	1,810
Payment of debt	(80,438)	(38,156)
Payments on revolving loan	0	(70,000)
Payment of deemed landlord liability	0	(1,387)
Net cash used in financing activities	(74,752)	(107,733)
EFFECT OF EXCHANGE RATES ON CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(753)	(889)
INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	56,008	(4,241)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — Beginning of period	23,282	26,492
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — End of period	$ 79,290	$ 22,251