Cover Page - shares	6 Months Ended
	Jun. 30, 2023	Aug. 01, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	001-38205
Entity Registrant Name	ZAI LAB LIMITED
Entity Incorporation, State or Country Code	E9
Entity Tax Identification Number	98-1144595
Entity Address, Address Line One	4560 Jinke Road
Entity Address, Address Line Two	Bldg. 1, Fourth Floor, Pudong
Entity Address, City or Town	Shanghai
Entity Address, Country	CN
Entity Address, Postal Zip Code	201210
City Area Code	86 21
Local Phone Number	6163 2588
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Central Index Key	0001704292
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false
American Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	American Depositary Shares, each representing 10 Ordinary Shares, par value $0.000006 per share
Trading Symbol	ZLAB
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		749,901,320
Ordinary Shares
Document Information [Line Items]
Title of 12(b) Security	Ordinary Shares, par value $0.000006 per share
Trading Symbol	9688
Entity Common Stock, Shares Outstanding		983,887,430