Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.21.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Mar. 18, 2021
Jun. 30, 2020
Document Information [Line Items]      
Document Type 10-K/A    
Amendment Flag false    
Document Annual Report true    
Document Transition Report false    
Document Period End Date Dec. 31, 2020    
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 Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Address, Address Line One 2 Gansevoort Street    
Entity Address, Address Line Two 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 Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 173,878,853
Entity Central Index Key 0001429260    
Document Fiscal Year Focus 2020    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
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   94,907,448  
9.375% Series A Cumulative Redeemable Perpetual Preferred Stock [Member]      
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