Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Mar. 08, 2018
Jun. 30, 2017
Document And Entity Information      
Entity Registrant Name THESTREET, INC.    
Entity Central Index Key 0001080056    
Document Type 10-K    
Trading Symbol TST    
Document Period End Date Dec. 31, 2017    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity a Well-known Seasoned Issuer No    
Entity a Voluntary Filer No    
Entity's Reporting Status Current Yes    
Entity Filer Category Smaller Reporting Company    
Entity Public Float     $ 26,000,000
Entity Common Stock, Shares Outstanding   49,186,690  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2017