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Related Party Agreements (Narrative) (Details) - USD ($) |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Jan. 01, 2021 | Jul. 22, 2016 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Proceeds from issuance of common shares |  |  |  |  | $ 0 | $ 37,230,000 |
At the Market Offering [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Proceeds from issuance of common shares |  |  |  |  | $ 66,900,000 | $ 25,600,000 |
Fortress Biotech, Inc [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Percentage of annual fees expense related to Management Services Agreement recorded in research and development expenses |  |  | 50.00% | 50.00% | 50.00% | 50.00% |
Percentage of annual fees expense related to Management Services Agreement recorded in general and administrative expenses |  |  | 50.00% | 50.00% | 50.00% | 50.00% |
Shares issued for services (in shares) | 2,001,490 |  |  |  | 517,304 |  |
Proceeds from issuance of common shares |  |  |  |  |  | $ 66,900,000 |
Percentage of fully diluted equity | 2.50% | 2.50% |  |  |  | 2.50% |
Expenses from related party transaction |  |  |  |  | $ 375,000 | $ 375,000 |
Fortress Biotech, Inc [Member] | Research and Development [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Expenses from related party transaction |  |  |  |  |  |  | $ 7,600,000
Fortress Biotech, Inc [Member] | General and Administrative [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Expenses from related party transaction |  |  |  |  | $ 1,700,000 |  |

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