Fortress Biotech, Inc. Quarterly report [Sections 13 or 15(d)]

Net Income (Loss) per Common Share (Schedule of Diluted Weighted Average Shares Outstanding) (Details)

Net Income (Loss) per Common Share (Schedule of Diluted Weighted Average Shares Outstanding) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of Series A preferred dividends on net loss per share calculation	$ 2.0	$ 2.0
Effect of partner company deemed dividends on net loss per share calculation	$ 0.1	$ 0.4
Potentially dilutive securities excluded from the computations of diluted weighted average shares outstanding	19,945,725	8,065,003
Warrants to purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the computations of diluted weighted average shares outstanding	14,396,201	5,769,788
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the computations of diluted weighted average shares outstanding	18,896	18,896
Unvested Restricted Stock and deferred Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the computations of diluted weighted average shares outstanding	3,093,923	1,902,386
Unvested Restricted Stock units and deferred Restricted Stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the computations of diluted weighted average shares outstanding	2,436,705	373,933