v2.4.0.8
Document and Entity Information
9 Months Ended
Sep. 30, 2015
Oct. 31, 2015
Document and Entity Information    
Entity Registrant Name COLLEGIUM PHARMACEUTICAL, INC  
Entity Central Index Key 0001267565  
Document Type 10-Q  
Document Period End Date Sep. 30, 2015  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   20,688,914
Document Fiscal Year Focus 2015  
Document Fiscal Period Focus Q3