Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document information
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Entity Registrant Name	Kiniksa Pharmaceuticals, Ltd.
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001730430
Amendment Flag	false
Common Shares
Document information
Entity Common Stock, Shares Outstanding		55,801,712
Class A common shares
Document information
Entity Common Stock, Shares Outstanding		22,285,129
Class B common shares
Document information
Entity Common Stock, Shares Outstanding		2,463,011
Class A1 common shares
Document information
Entity Common Stock, Shares Outstanding		14,995,954
Class B1 common shares
Document information
Entity Common Stock, Shares Outstanding		16,057,618