Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (49,144)	$ (82,394)
Adjustments to reconcile net loss to net cash used in operating activities:
Allowance for credit loss (gain)	1	(1)
Inventory write-down	377	138
Depreciation and amortization expenses	2,657	2,013
Amortization of deferred income	(582)	(708)
Share-based compensation	16,661	12,410
Share of loss from equity method investment	0	221
(Gain) Loss from fair value changes of equity investment with readily determinable fair value	(441)	6,939
Loss (gain) on disposal of property and equipment	64	(11)
Non-cash lease expenses	2,464	2,017
Foreign currency remeasurement gain	(8,912)	(2,285)
Changes in operating assets and liabilities:
Accounts receivable	(2,852)	14,080
Notes receivable	(8,599)	(3,513)
Inventories	(6,686)	(1,475)
Prepayments and other current assets	(6,470)	1,531
Long-term deposits	72	(71)
Value added tax recoverable	0	3,092
Accounts payable	(327)	(28,002)
Other current liabilities	(15,593)	(8,837)
Operating lease liabilities	(2,141)	(2,389)
Deferred income	9,839	118
Other non-current liabilities	325	0
Net cash used in operating activities	(69,287)	(87,127)
Cash flows from investing activities
Purchases of short-term investments	(100,000)	(120,274)
Proceeds from maturity of short-term investment	49,450	100,000
Disposal of property and equipment	112	25
Purchases of property and equipment	(3,513)	(9,743)
Purchases of intangible assets	(3)	(152)
Net cash used in investing activities	(53,954)	(30,144)
Cash flows from financing activities
Proceeds from exercises of stock options	1,197	297
Employee taxes paid related to settlement of equity awards	(5,083)	(39)
Net cash (used in) provided by financing activities	(3,886)	258
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(1,299)	(130)
Net decrease in cash, cash equivalents and restricted cash	(128,426)	(117,143)
Cash, cash equivalents and restricted cash - beginning of period	1,009,273	964,903
Cash, cash equivalents and restricted cash - end of period	880,847	847,760
Supplemental disclosure on non-cash investing and financing activities
Payables for purchase of property and equipment	4,232	668
Payables for intangible assets	268	73
Payables for treasury stock	0	55
Receivables for stock option exercise under equity incentive plans	476	0
Right-of-use asset acquired under operating leases	2,662	4,596
Receivables for dispose of property and equipment	10	0
Supplemental disclosure of cash flow information:
Cash and cash equivalents	879,844	846,957
Restricted cash, non-current	1,003	803
Total cash and cash equivalents and restricted cash	$ 880,847	$ 847,760