Annual report pursuant to Section 13 and 15(d)

Notes Payable (Details Textual)

v3.19.1
Notes Payable (Details Textual) - USD ($)
1 Months Ended 12 Months Ended
Jul. 05, 2017
Jun. 26, 2017
Jun. 25, 2017
Dec. 30, 2016
Sep. 30, 2016
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Feb. 28, 2015
Repayments of Notes Payable           $ 0 $ 3,000,000    
Debt Instrument, Periodic Payment, Interest     $ 100,000            
Stock Issued During Period, Shares, New Issues         250,000        
Stock Issued During Period, Value, New Issues           0 948,000    
Notes Payable           0 0 $ 2,826,000  
Convertible Debt, Fair Value Disclosures       $ 200,000          
Debt Conversion, Converted Instrument, Shares Issued   49,748              
IPO [Member]                  
Stock Issued During Period, Shares, New Issues   6,325,000              
Fortress Biotech, Inc [Member] | IPO [Member]                  
Stock Issued During Period, Shares, New Issues   125,000              
Stock Issued During Period, Value, New Issues   $ 800,000              
NSC Notes Memebers [Member]                  
Repayments of Notes Payable $ 3,000,000           3,000,000 3,000,000  
Debt Instrument, Periodic Payment, Interest $ 2,000                
Notes Payable             0    
Debt Instrument, Unamortized Discount           $ 0 $ 0 174,000  
NSC Notes Memebers [Member] | IPO [Member]                  
Stock Issued During Period, Value, New Issues   125,000              
NSC Notes Memebers [Member] | Fortress Biotech, Inc [Member]                  
Debt Instrument, Term           10 years      
Debt Instrument, Interest Rate, Stated Percentage           8.00%      
Debt Instrument, Maturity Date, Description           The note matures in 36 months, provided that during the first 24 months Fortress can extend the maturity date by six months. No principal amount will be due for the first 24 months (or the first 30 months if the maturity date is extended). Thereafter      
Contingently Issuable Warrants Percentage           25.00%      
Debt Issuance Costs, Net               $ 200,000  
Debt Instrument, Interest Rate, Effective Percentage               13.10%  
Debt Instrument, Unamortized Discount               $ 100,000  
NSC Notes Memebers [Member] | Avenue Therepeutics parent co [Member]                  
Debt Instrument, Face Amount   $ 3,000,000             $ 10,000,000
Convertible Note Payable [Member] | Fortress Biotech, Inc [Member]                  
Debt Instrument, Term       18 months          
Convertible Notes Payable, Current       $ 200,000          
Debt Instrument Interest Rate Stated Percentage current Year       5.00%          
Debt Instrument Interest Rate Stated Percentage after Twelve Month       8.00%          
Proceeds from Issuance or Sale of Equity       $ 10,000,000          
Net Proceeds From Issuance Of Private Placement After Paying Fees       100,000          
Payments For Placement Fee       30,000          
Payments for Other Fees       4,000          
Professional Fees       14,000          
Class Of Warrant Or Right Value Of Securities Called By Warrants Or Rights       10,000          
Maximum Threshold Limit for Conversion into Equity       $ 10,000,000          
Convertible Note Payable [Member] | Fortress Biotech, Inc [Member] | Conversion One [Member]                  
Debt Instrument, Convertible, Terms of Conversion Feature       (a) the lowest price per share at which equity securities of Avenue are sold in such sale less a 33% discount and (b) a per share price based on a pre-offering valuation of $30.0 million divided by the number of common shares outstanding on a fully-diluted basis.          
Convertible Note Payable [Member] | Fortress Biotech, Inc [Member] | Conversion Two [Member]                  
Debt Instrument, Convertible, Terms of Conversion Feature       (a) a discount to the price per share being paid in the Sale of Avenue equal to 33% or (b) the quotient resulting from dividing (x) $30.0 million by (y) the fully-diluted common stock of Avenue outstanding immediately prior to the Sale of Avenue (excluding the notes)