v3.8.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Apr. 16, 2018
Jun. 30, 2017
Document And Entity Information      
Entity Registrant Name CM Seven Star Acquisition Corp    
Entity Central Index Key 0001713539    
Document Type 10-K    
Trading Symbol CMSS    
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     $ 0
Entity Common Stock, Shares Outstanding   26,323,092  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2017