CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net income	$ 6,501	$ 25,510
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,870	8,540
Bad debt expense	948	1,835
Deferred taxes	(5,758)	(3,654)
Share-based compensation expense	8,121	6,889
Changes in operating assets and liabilities:
Accounts receivable	5,044	16,033
Prepaid expenses and other current assets	453	(992)
Deposits and other assets	(344)	(275)
Accounts payable and accrued expenses	(7,775)	(15,472)
Accrued compensation and employee benefits	(3,015)	(10,712)
Deferred revenue and advance payments	10,502	11,058
Other long-term liabilities	4,780	(1,647)
Net cash provided by operating activities	23,327	37,113
Investing activities:
Proceeds from redemption of short-term investments	245,680	151,860
Purchases of property and equipment	(2,644)	(1,467)
Purchases of short-term investments	(596,376)	(216,602)
Net cash used in investing activities	(353,340)	(66,209)
Financing activities:
Proceeds from sale of class A common stock under exercise of employee stock options	2,471	1,677
Payments on capital lease obligations and other financing arrangements	(9)	(12)
Net cash provided by financing activities	2,462	1,665
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	(2,240)	5,246
Net decrease in cash, cash equivalents, and restricted cash	(329,791)	(22,185)
Cash, cash equivalents and restricted cash, beginning of period	421,182	402,712
Cash, cash equivalents and restricted cash, end of period	$ 91,391	$ 380,527