CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 28,954	$ 19,198
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	2,453	1,991
Amortization	1,997	5,844
Stock-based compensation expense	5,445	3,183
Amortization of debt issuance costs and discount	0	138
Noncash lease expense	2,917	2,363
Deferred income tax provision	1,079	656
Amortization and adjustment of deferred credit	(181)	(200)
Other	(67)	(43)
Changes in assets and liabilities:
Accounts receivable and unbilled, net	19,301	4,255
Prepaid expenses and other current assets	(2,694)	(1,642)
Accounts payable	(6,809)	(2,684)
Accrued expenses	(1,757)	(5,221)
Advanced billings	(2,695)	2,437
Lease liabilities	(2,236)	(2,041)
Other assets and liabilities, net	3,441	5,771
Net cash provided by operating activities	49,148	34,005
CASH FLOWS FROM INVESTING ACTIVITIES:
Property and equipment expenditures	(5,561)	(2,520)
Other	39	(1,322)
Net cash used in investing activities	(5,522)	(3,842)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock option exercises	1,331	972
Repurchases of common stock	(41,776)	0
Payment of debt	0	(24,000)
Net cash used in financing activities	(40,445)	(23,028)
EFFECT OF EXCHANGE RATES ON CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(1,102)	(290)
INCREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	2,079	6,845
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — Beginning of period	131,920	23,282
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — End of period	$ 133,999	$ 30,127