Unaudited condensed consolidated statements of cash flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net loss	$ (220,327)	$ (396,234)
Adjustments to reconcile net loss to net cash used in operating activities:
Allowance for credit loss	(3)	4
Inventory write-down	193	290
Depreciation and amortization expenses	3,874	2,975
Amortization of deferred income	(1,386)	(156)
Share-based compensation	26,634	17,550
Noncash research and development expenses	0	62,250
Share of loss from equity method investment	221	208
Loss from fair value changes of equity investment with readily determinable fair value	12,556	0
(Gain) loss on disposal of property and equipment	(11)	4
Noncash lease expenses	3,825	2,779
Changes in operating assets and liabilities:
Accounts receivable	20,422	(12,868)
Notes receivable	(3,633)	0
Inventories	(4,582)	1,740
Prepayments and other current assets	48	(1,953)
Long-term deposits	(78)	(29)
Value added tax recoverable	23,602	(1,682)
Accounts payable	(17,718)	62,980
Other current liabilities	29,510	28,078
Operating lease liabilities	(3,849)	(2,214)
Deferred income	(1,325)	930
Net cash used in operating activities	(132,027)	(235,348)
Cash flows from investing activities:
Purchases of short-term investments	(260,274)	0
Proceeds from maturity of short-term investment	130,000	743,902
Purchase of property and equipment	(13,488)	(5,647)
Purchase of intangible assets	(107)	(427)
Net cash (used in) provided by investing activities	(143,869)	737,828
Cash flows from financing activities:
Proceeds from exercises of stock options	4,619	3,992
Proceeds from issuance of ordinary shares upon public offerings	0	818,874
Payment of public offering costs	0	(1,323)
Employee taxes paid related to net share settlement of equity awards	(6,859)	(594)
Net cash (used in) provided by financing activities	(2,240)	820,949
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(5,144)	1,028
Net (decrease) increase in cash, cash equivalents and restricted cash	(283,280)	1,324,457
Cash, cash equivalents and restricted cash - beginning of period	964,903	442,859
Cash, cash equivalents and restricted cash - end of period	681,623	1,767,316
Supplemental disclosure on non-cash investing and financing activities:
Payables for purchase of property and equipment	1,661	1,720
Payables for intangible assets	270	58
Payables for public offering costs	0	555
Payables for treasury stock	17	0
Receivables for stock option exercise under equity incentive plans	12	0
Right-of-use asset acquired under operating leases	8,451	0
Supplemental disclosure of cash flow information:
Cash and cash equivalents	680,820	1,766,573
Restricted cash, non-current	803	743
Total cash and cash equivalents and restricted cash	$ 681,623	$ 1,767,316