Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies (Narrative) (Details)

v3.21.1
Significant Accounting Policies (Narrative) (Details)
 12 Months Ended
Mar. 29, 2019
Jul. 26, 2016
Jul. 22, 2016
shares
Dec. 31, 2020
USD ($)
segment
item
shares
Dec. 31, 2019
USD ($)
shares
Class of Stock [Line Items]          
Number of subsidiaries | item       0  
Number of operating segments | segment       1  
Number of reportable segments | segment       1  
Estimated useful life       5 years  
Property, plant and equipment, gross       $ 11,595,000 $ 9,826,000
Restricted cash       1,000,000.0 1,000,000.0
Research and development expense       37,237,000 30,042,000
Accumulated other comprehensive loss       0  
Construction in Process [Member]          
Class of Stock [Line Items]          
Property, plant and equipment, gross       $ 499,000 $ 1,157,000
Fortress Biotech, Inc [Member]          
Class of Stock [Line Items]          
Common stock dividend issued (in shares) | shares       2,001,490 1,206,667
Percentage of fully diluted equity   2.50% 2.50% 2.50% 2.00%
Fortress Biotech, Inc [Member] | At the Market Offering [Member]          
Class of Stock [Line Items]          
Percentage of fully diluted equity       2.50% 2.50%
Fortress Biotech, Inc [Member] | Issuance Related to Debt Financing [Member]          
Class of Stock [Line Items]          
Percentage of fully diluted equity 2.50%       2.50%
Fortress Biotech, Inc [Member] | License Agreements [Member]          
Class of Stock [Line Items]          
Research and development expense       $ 7,600,000 $ 4,900,000
Fortress Biotech, Inc [Member] | Preferred Class A [Member]          
Class of Stock [Line Items]          
Preferred stock dividends issued (in shares) | shares     250,000    
Percentage of fully diluted equity     2.50%