Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 30,840	$ 27,259
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	24,806	26,532
Stock-based compensation expense	12,504	14,111
Amortization of operating lease right-of-use assets	13,703	13,701
Unrealized gain on short term investments	(2,842)	(4,362)
Unrealized foreign exchange (gain)/loss, net	(3,316)	1,967
Deferred income tax expense/(benefit)	(663)	(2,631)
Allowance for expected credit losses	389	281
Loss from equity-method investment	121	129
Amortization of non-cash interest expense related to convertible senior notes	1,289	1,218
Impairment charges	0	3,167
Others, net	(1,204)	961
Change in operating assets and liabilities:
Accounts receivable	12,380	(16,478)
Prepaid expenses and other current assets	(1,091)	(2,033)
Advance income tax, net	4,446	1,345
Other assets	3,046	126
Accounts payable	1,943	(2,114)
Deferred revenue	3,066	5,654
Accrued employee costs	(23,497)	(12,567)
Accrued expenses and other liabilities	(4,182)	5,200
Operating lease liabilities	(12,831)	(13,749)
Net cash provided by operating activities	58,907	47,717
Cash flows from investing activities:
Purchases of property and equipment	(22,051)	(22,287)
Investment in equity affiliate	(700)	0
Purchase of non-controlling interest	0	(241)
Purchase of investments	(49,027)	(68,188)
Proceeds from redemption of investments	72,844	91,669
Net cash provided by investing activities	1,066	953
Cash flows from financing activities:
Principal payments of finance lease liabilities	(124)	(207)
Proceeds from borrowings	110,000	46,000
Repayments of borrowings	(110,210)	(79,590)
Payment of debt issuance costs	0	(117)
Acquisition of treasury stock	(13,995)	(27,538)
Proceeds from exercise of stock options	960	338
Net cash used for financing activities	(13,369)	(61,114)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(2,873)	(240)
Net increase/(decrease) in cash, cash equivalents and restricted cash	43,731	(12,684)
Cash, cash equivalents and restricted cash at the beginning of the period	127,044	104,131
Cash, cash equivalents and restricted cash at the end of the period	$ 170,775	$ 91,447