Fortress Biotech, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Narrative) (Details)

Fair Value Measurements (Narrative) (Details) $ / shares in Units, $ in Thousands						1 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended
	Nov. 14, 2023 USD ($)	Jan. 27, 2023 USD ($) $ / shares shares	Dec. 30, 2022 USD ($) shares	Dec. 16, 2022 USD ($)	Oct. 11, 2022 USD ($) item $ / shares shares	Jul. 31, 2023 USD ($)	Feb. 28, 2023 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares	Sep. 30, 2023 USD ($) $ / shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Jun. 13, 2023 $ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of retained investment								$ 2,600	$ 2,600
Sale of stock, net proceeds	$ 8,900		$ 150,000			$ 9,100	$ 6,700
Gain (loss) on common stock warrant liabilities								(4,542)	(10,708)
Common stock, value								9	9		$ 7
Stock offering, price per share \| $ / shares							$ 5.25
Stock offering, number of shares issued \| shares			4,900,000				1,180,000
Common stock warrant liabilities								$ 5,430	5,430		13,869
Number of shares called by warrants \| shares							1
Exercise price of warrants \| $ / shares												$ 8.136
Proceeds from issuance of common stock for at-the-market offering, net									$ 2,056	$ 5,750
Share Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Retained investment, deconsolidated subsidiary, measurement input \| $ / shares								0.328	0.328
Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Retained investment, deconsolidated subsidiary, measurement input								0.037	0.037
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Retained investment, deconsolidated subsidiary, measurement input								0.80	0.80
Discount for lack of marketability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Retained investment, deconsolidated subsidiary, measurement input								0.397	0.397
Pre funded warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock offering, price per share \| $ / shares							$ 5.2499
Checkpoint Common Stock Warrants \| Common Stock Warrant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on common stock warrant liabilities									$ 9,200
Checkpoint Common Stock Warrants \| 2022 Director Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Sale of stock, net proceeds				$ 6,700
Avenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock offering, number of shares issued \| shares		448,000
Shares issued \| shares					3,636,365
Number of common stock (in units) \| item					1
Number of warrants (in units) \| item					1
Warrants issued \| shares					545,454
Proceeds from issuance of common stock for at-the-market offering, net					$ 10,300
Avenue \| Contingent Conditions are Met [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net proceeds		$ 2,800
Stock offering, number of shares issued \| shares		1,940,299
Common stock warrant liabilities		$ 2,200
Number of shares called by warrants \| shares		1
Exercise price of warrants \| $ / shares		$ 0.125
Unit Price Per Share \| $ / shares		1.55
Avenue \| Pre funded warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of warrants (in units) \| item					1
Exercise price of warrants \| $ / shares					$ 0.0001
Unit Price Per Share \| $ / shares					$ 3.2999
Avenue \| Common Stock and Pre-funded Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of warrants (in units) \| item					1
Unit Price Per Share \| $ / shares					$ 3.30
Common Stock Warrant \| Checkpoint Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on common stock warrant liabilities									(9,179)
Common stock warrant liabilities								$ 1,991	1,991		11,170
Common Stock Warrant \| Avenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Issuance of Warrants									2,235		8,300
Gain (loss) on common stock warrant liabilities									(1,544)
Common stock warrant liabilities								3,300	3,300		2,609
Number of common stock (in units) \| item					1
Number of warrants (in units) \| item					1
Common Stock Warrant \| Avenue \| Common Stock Warrant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock offering, price per share \| $ / shares		$ 1.55
Common Stock Warrant \| Avenue \| Pre funded warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of shares called by warrants \| shares		1,492,299
Exercise price of warrants \| $ / shares		$ 0.001
Unit Price Per Share \| $ / shares		$ 1.549
Placement Agent Warrants \| Urica
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Issuance of Warrants									33
Gain (loss) on common stock warrant liabilities									16
Contingent Payment Warrants \| Urica
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants								$ 100	$ 100		$ 100