Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2018
Mar. 12, 2019
Jun. 29, 2018
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, 2018    
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 Emerging Growth false    
Entity Small Business true    
Entity Shell Company false    
Entity Filer Category Non-accelerated Filer    
Entity Public Float     $ 66,000,000
Entity Common Stock, Shares Outstanding   51,563,410  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2018