CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net income	$ 36,178	$ 31,931
Adjustments to reconcile net income to net cash (used for)/provided by operating activities:
Depreciation and amortization expense	13,669	12,266
Stock-based compensation expense	11,224	7,832
Amortization of operating lease right-of-use assets	6,043	6,761
Unrealized gain on short term investments	(384)	(1,103)
Unrealized foreign currency exchange gain, net	(3,165)	(1,139)
Deferred income tax benefit	(193)	(2,695)
Allowance for expected credit losses	34	48
Gain/(loss) from equity-method investment	(114)	36
Amortization of non-cash interest expense related to convertible senior notes	0	673
Others, net	819	216
Change in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(45,659)	(11,818)
Prepaid expenses and other current assets	(1,116)	(21)
Advance income tax, net	6,185	9,057
Other assets	(2,924)	1,268
Accounts payable	(808)	1,902
Deferred revenue	3,707	(17,986)
Accrued employee costs	(60,008)	(23,611)
Accrued expenses and other liabilities	15,647	8,456
Operating lease liabilities	(6,005)	(6,868)
Net cash (used for)/provided by operating activities	(26,870)	15,205
Cash flows from investing activities:
Purchases of property and equipment	(16,101)	(12,680)
Proceeds from sale of property and equipment	63	129
Business acquisition (net of cash and cash equivalents acquired)	(1,367)	0
Purchases of investments	(36,804)	(18,835)
Proceeds from redemption of investments	49,515	5,357
Net cash used for investing activities	(4,694)	(26,029)
Cash flows from financing activities:
Principal payments of finance lease liabilities	(39)	(57)
Proceeds from borrowings	35,000	25,000
Repayments of borrowings	0	(25,000)
Acquisition of treasury stock	(31,385)	(29,015)
Proceeds from exercise of stock options	0	75
Net cash provided by/(used for) financing activities	3,576	(28,997)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(753)	(984)
Net decrease in cash, cash equivalents and restricted cash	(28,741)	(40,805)
Cash, cash equivalents and restricted cash at the beginning of the period	143,810	225,519
Cash, cash equivalents and restricted cash at the end of the period	115,069	184,714
Cash paid during the period for:
Interest	1,277	610
Income taxes, net of refunds	5,404	2,415
Supplemental disclosure of non-cash investing and financing activities:
Assets acquired under finance lease	$ 50	$ 10