Document and Entity Information - shares
6 Months Ended
Jun. 30, 2018
Aug. 13, 2018
Document And Entity Information    
Entity Registrant Name Celsion CORP  
Entity Central Index Key 0000749647  
Document Type 10-Q  
Document Period End Date Jun. 30, 2018  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Filer Category Smaller Reporting Company  
Entity Common Stock, Shares Outstanding   17,746,285
Trading Symbol CLSN  
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2018