Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Feb. 15, 2019
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	SVMK
Entity Registrant Name	SVMK Inc.
Entity Central Index Key	0001739936
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	false
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		126,644,497
Entity Public Float	$ 803,964,000