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Stockholders' Equity (Details) |  |  |  |  | 1 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2020 | Jan. 01, 2019 | Jul. 31, 2016 $ / shares shares | Jul. 26, 2016 | Nov. 30, 2019 shares | May 31, 2019 USD ($) shares | Apr. 30, 2019 USD ($) $ / shares shares | Mar. 29, 2019 shares | Dec. 31, 2019 USD ($) item $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Sep. 30, 2019 shares | Aug. 16, 2019 $ / shares shares | Aug. 15, 2019 shares | Jul. 31, 2018 USD ($) | Dec. 31, 2016 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  | 50,000,000 |  |  |  |  |  | 85,000,000 | 85,000,000 |  | 85,000,000 | 50,000,000 |  |
Common stock par value (in dollars per share) | $ / shares |  |  | $ 0.0001 |  |  |  |  |  | $ 0.0001 | $ 0.0001 |  |  |  |  |
Common stock issuable, shares |  |  |  |  |  |  |  |  | 1,206,667 | 709,314 |  |  |  |  |
Aggregate value of shares subscribed | $ |  |  |  |  |  |  |  |  | $ 4,923,000 | $ 2,085,000 |  |  |  |  |
Common stock, number of shares issued |  |  |  |  |  |  |  |  | 39,403,519 | 26,610,183 |  |  |  |  |
Issuance of common shares, net of offering costs - Public Offering | $ |  |  |  |  |  |  |  |  | $ 29,537,000 |  |  |  |  |  |
Proceeds from issuance of common stock and warrants, offering cost | $ |  |  |  |  |  |  |  |  | 2,088,000 | $ 0 |  |  |  |  |
Stock dividend (as a percent) | 2.50% | 2.00% | 2.50% |  |  |  |  |  |  |  |  |  |  |  |
Fortress Biotech, Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate value of shares subscribed | $ |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 900
Stock dividend (as a percent) |  |  |  | 2.50% |  |  |  |  |  |  |  |  |  |  |
At The Market Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of common shares | $ |  |  |  |  |  |  |  |  | $ 22,000,000 |  |  |  |  |  |
Maximum value of shares authorized to sell at offering | $ |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 75,000,000 |
Agent commission (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.00% |
Common stock, number of shares issued |  |  |  |  |  |  |  |  | 3,500,000 |  |  |  |  |  |
Share price | $ / shares |  |  |  |  |  |  |  |  | $ 6.42 |  |  |  |  |  |
Issuance of common shares, net of offering costs - Public Offering | $ |  |  |  |  |  |  |  |  | $ 22,500,000 |  |  |  |  |  |
Proceeds from issuance of common stock and warrants, offering cost | $ |  |  |  |  |  |  |  |  | 500,000 |  |  |  |  |  |
At The Market Offering | Fortress Biotech, Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share of equity or debt financing used to calculate equity fee or stock issuance to maintain parity (as a percent) |  |  |  |  |  | 2.50% | 2.50% |  |  |  |  |  |  |  |
Shares issued for services (in shares) |  |  |  |  |  | 197,656 | 87,656 |  |  |  |  |  |  |  |
Proceeds from issuance of common shares | $ |  |  |  |  |  | $ 31,600,000 | $ 22,500,000 |  |  |  |  |  |  |  |
Issuances Related To Debt Financing | Fortress Biotech, Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued for services (in shares) |  |  |  |  |  |  |  | 108,069 |  |  |  |  |  |  |
Stock dividend (as a percent) |  |  |  |  |  |  |  | 2.50% |  |  |  |  |  |  |
Public Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of common shares | $ |  |  |  |  |  |  | $ 29,500,000 |  |  |  |  |  |  |  |
Maximum value of shares authorized to sell at offering | $ |  |  |  |  |  |  |  |  | 75,000,000 |  |  |  |  |  |
Securities available for sale | $ |  |  |  |  |  |  |  |  | $ 20,900,000 |  |  |  |  |  |
Share price | $ / shares |  |  |  |  |  |  | $ 4.00 |  |  |  |  |  |  |  |
Issuance of common shares and warrants for cash (in shares) |  |  |  |  |  |  | 6,875,000 |  |  |  |  |  |  |  |
Issuance of common shares, net of offering costs - Public Offering | $ |  |  |  |  |  |  | $ 31,600,000 |  |  |  |  |  |  |  |
Proceeds from issuance of common stock and warrants, offering cost | $ |  |  |  |  |  |  | $ 2,100,000 |  |  |  |  |  |  |  |
Over-Allotment Option [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common shares and warrants for cash (in shares) |  |  |  |  |  |  | 1,031,250 |  |  |  |  |  |  |  |
Common Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  |  |  |  |  |  |  | 85,000,000 |  |  |  |
Common stock par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 0.0001 |  |  |
Number of votes per share | item |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |
Common Shares | City Of Hope National Medical Center ("COH") [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in conversion |  |  |  |  | 17,007 |  | 137,608 |  |  |  |  |  |  |  |
Common Shares | Fortress Biotech, Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issuable, shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000,000
Class A Common Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued for services (in shares) |  |  |  |  |  |  |  |  | 0 | 0 |  |  |  |  |
Number of shares converted |  |  |  |  |  |  |  |  | (154,615) |  |  |  |  |  |
Common stock, shares authorized |  |  | 1,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Director appointment right, period |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |  |
Number of directors appointable | item |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |
Common stock, number of shares issued |  |  |  |  |  |  |  |  | 845,385 | 1,000,000 |  |  |  |  |
Issuance of common shares and warrants for cash (in shares) |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |
Issuance of common shares, net of offering costs - Public Offering | $ |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  |  |
Class A Common Shares | City Of Hope National Medical Center ("COH") [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares converted |  |  |  |  | 17,007 |  | 137,608 |  | 154,615 |  |  |  |  |  |
Common Class B |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  | 15,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Number of votes per share | item |  |  |  |  |  |  |  |  | 1.1 |  |  |  |  |  |
Common Class B | Fortress Biotech, Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issuable, shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,000,000

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