Financial Statements Schedule I - Condensed Statements of Operations and Comprehensive Loss (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Expenses:
Research and development	$ (286,408,000)	$ (573,306,000)	$ (222,711,000)
Loss from operations	(404,357,000)	(700,064,000)	(301,801,000)
Interest income	14,582,000	2,190,000	5,120,000
Other (expenses) income, net	3,113,000	(10,201,000)	7,417,000
Loss before income tax and share of loss from equity method investment	(443,065,000)	(703,414,000)	(267,786,000)
Income tax expense	0	0	0
Net loss	(443,286,000)	(704,471,000)	(268,905,000)
Other comprehensive income (loss) , net of tax of nil:
Other comprehensive (loss) income, tax	0	0	0
Foreign currency translation adjustments	49,330,000	(9,121,000)	(19,144,000)
Comprehensive loss	(393,956,000)	(713,592,000)	(288,049,000)
Parent Company
Operating Expenses:
Research and development	(178,000)	(6,000)	(437,000)
General and administrative	(19,773,000)	(12,074,000)	(7,345,000)
Loss from operations	(19,951,000)	(12,080,000)	(7,782,000)
Interest income	12,857,000	1,881,000	4,899,000
Other (expenses) income, net	(8,678,000)	(18,173,000)	312,000
Loss before income tax and share of loss from equity method investment	(15,772,000)	(28,372,000)	(2,571,000)
Equity in loss of subsidiaries	(427,514,000)	(676,099,000)	(266,334,000)
Income tax expense	0	0	0
Net loss	(443,286,000)	(704,471,000)	(268,905,000)
Other comprehensive income (loss) , net of tax of nil:
Other comprehensive (loss) income, tax	0	0	0
Foreign currency translation adjustments	49,330,000	(9,121,000)	(19,144,000)
Comprehensive loss	$ (393,956,000)	$ (713,592,000)	$ (288,049,000)