Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Feb. 22, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name TENABLE HOLDINGS, INC.  
Entity Central Index Key 0001660280  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Document Type 10-K  
Document Period End Date Dec. 31, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus FY  
Amendment Flag false  
Entity Common Stock, Shares Outstanding (in shares)   94,955,182
Entity Emerging Growth Company true  
Entity Small Business false  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Public Float $ 687.5