CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net income	$ 4,044	$ 12,488
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,828	3,623
Reduction in carrying amount of right-of-use assets	4,085	4,064
Credit losses and sales allowances	990	796
Net realized loss on short-term investments	0	41
Deferred taxes	273	(3,219)
Share-based compensation expense	5,337	6,053
Changes in operating assets and liabilities:
Accounts receivable	21,022	5,985
Prepaid expenses and other current assets	(493)	7,089
Deposits and other assets	195	96
Accounts payable and accrued expenses	(1,823)	(8,396)
Accrued compensation and employee benefits	(8,708)	(8,082)
Deferred revenue and advance payments	347	33,489
Operating lease liabilities	(4,662)	(4,316)
Other long-term liabilities	86	(509)
Net cash provided by operating activities	26,521	49,202
Investing activities:
Proceeds from redemption of short-term investments	10,000	369,603
Purchases of property and equipment	(1,162)	(8,432)
Purchases of short-term investments	(9,928)	(212,248)
Net cash (used in) provided by investing activities	(1,090)	148,923
Financing activities:
Proceeds from sale of class A common stock under exercise of employee stock options	1,902	1,836
Purchases of treasury stock	(61,875)	(48,244)
Net cash used in financing activities	(59,973)	(46,408)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	(1,154)	33
Net (decrease) increase in cash, cash equivalents, and restricted cash	(35,696)	151,750
Cash, cash equivalents, and restricted cash, beginning of period	457,816	110,786
Cash, cash equivalents, and restricted cash, end of period	$ 422,120	$ 262,536