Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.20.2
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2020
Nov. 05, 2020
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2020  
Document Transition Report false  
Entity File Number 001-35366  
Entity Registrant Name Fortress Biotech, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 20-5157386  
Entity Address, Address Line One 2 Gansevoort Street, 9th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10014  
City Area Code 781  
Local Phone Number 652-4500  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Central Index Key 0001429260  
Document Fiscal Year Focus 2020  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q3  
Common Stock [Member]    
Document Information [Line Items]    
Title of 12(b) Security Common Stock  
Trading Symbol FBIO  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   93,702,861
9.375% Series A Cumulative Redeemable Perpetual Preferred Stock    
Document Information [Line Items]    
Title of 12(b) Security 9.375% Series A Cumulative Redeemable Perpetual Preferred Stock  
Trading Symbol FBIOP  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   3,427,138