Income Tax - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Line Items]
Taxable income	$ (334,620,000)	$ (443,286,000)	$ (704,471,000)
Provision for income taxes	0	0	0
Net operating loss carry forwards	1,804,900,000	1,483,200,000
Mainland China
Income Tax Disclosure [Line Items]
Taxable income	(253,274,000)	(290,056,000)	(340,865,000)
Net operating loss carry forwards	1,492,000,000
Hong Kong
Income Tax Disclosure [Line Items]
Taxable income	(4,483,000)	(53,425,000)	(243,400,000)
Net operating loss carry forwards	51,000,000.0
Taiwan
Income Tax Disclosure [Line Items]
Taxable income	(772,000)	(989,000)	(671,000)
Net operating loss carry forwards	2,100,000
United States
Income Tax Disclosure [Line Items]
Taxable income	(92,869,000)	(79,620,000)	(89,374,000)
Net operating loss carry forwards	256,000,000.0
Australia
Income Tax Disclosure [Line Items]
Taxable income	(14,000)	260,000	(1,758,000)
Net operating loss carry forwards	3,800,000
Zai Lab (AUST) Pty. Ltd.
Income Tax Disclosure [Line Items]
Taxable income	0
Provision for income taxes	0
Zai Lab (US) LLC
Income Tax Disclosure [Line Items]
Taxable income	0
Provision for income taxes	0
Zai Lab (Taiwan) Limited
Income Tax Disclosure [Line Items]
Taxable income	0
Provision for income taxes	0
Zai Lab (Hong Kong) and ZL China Holding Two and Zai Auto Immune (Hong Kong) and Zai Anti Infectives (Hong Kong) Limited
Income Tax Disclosure [Line Items]
Taxable income	0	0	0
Provision for income taxes	0	0	0
Withholding taxes on remittance of dividends	$ 0	$ 0	$ 0