DEI Document - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 29, 2020	Jun. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	XERIS PHARMACEUTICALS INC
Entity Central Index Key	0001346302
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Accelerated Filer
Entity Voluntary Filers	No
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Trading Symbol	XERS
Title of 12(b) Security	Common stock, $0.0001 par value per share
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		37,570,080
Entity Listing, Par Value Per Share	$ 0.0001
Entity Public Float			$ 227.2