Income Tax - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Line Items]
Taxable income	$ (257,103,000)	$ (334,620,000)	$ (443,286,000)
Provision for income taxes	0	0	0
Net operating loss carry forwards	1,951,500,000	1,804,900,000
Mainland China
Income Tax Disclosure [Line Items]
Taxable income	(146,725,000)	(253,274,000)	(290,056,000)
Hong Kong
Income Tax Disclosure [Line Items]
Taxable income	(1,808,000)	(4,483,000)	(53,425,000)
Operating loss not subject to expiration	57,700,000
Taiwan
Income Tax Disclosure [Line Items]
Taxable income	(582,000)	(772,000)	(989,000)
Operating loss subject to expiration	2,500,000
United States
Income Tax Disclosure [Line Items]
Taxable income	(110,422,000)	(92,869,000)	(79,620,000)
Operating loss not subject to expiration	306,900,000
Australia
Income Tax Disclosure [Line Items]
Taxable income	(19,000)	(14,000)	260,000
Operating loss not subject to expiration	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
Certain Entity | Mainland China
Income Tax Disclosure [Line Items]
Operating loss subject to expiration	1,497,000,000
Other Entities | Mainland China
Income Tax Disclosure [Line Items]
Operating loss subject to expiration	$ 83,600,000