Fortress Biotech, Inc. Annual report [Section 13 and 15(d), not S-K Item 405]

License Agreements (Journey and Other Narrative) (Details)

License Agreements (Journey and Other Narrative) (Details) $ in Thousands, ¥ in Billions			1 Months Ended						3 Months Ended	12 Months Ended
	Oct. 01, 2023 JPY (¥)	Aug. 31, 2023 USD ($)	Dec. 31, 2024 USD ($)	Jan. 31, 2024 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021	Jul. 31, 2020 USD ($) Milestone	Jul. 31, 2019 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones										$ 700	$ 500
Other revenue										1,000	19,519
Purchase of intangible asset										$ 15,000	5,000
Journey
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones									$ 15,000
Journey \| Dr. Reddy's Laboratories, Ltd
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Purchase of intangible asset							$ 5,000
Accutane agreement							10 years
Period of written notice							180 days
Journey \| Dr. Reddy's Laboratories, Ltd \| Achievement of Certain Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones							$ 17,000
Number of development milestones \| Milestone							3
Journey \| Maruho Co Ltd
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees payment		$ 19,000
Payments of milestones		45,000
Other revenue											$ 19,000
Net Sales \| ¥	¥ 4
Journey \| Maruho Co Ltd \| Maruho achieving net sales of ¥4 billion (yen) in single fiscal year
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones		$ 10,000
Journey \| Minimum \| Period of first two years of product
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Asset purchase agreement, percentage of royalties						30.00%
Journey \| Minimum \| Period of year three through year ten of product
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Asset purchase agreement, percentage of royalties						12.00%
Journey \| Maximum \| Period of first two years of product
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Asset purchase agreement, percentage of royalties						40.00%
Journey \| Maximum \| Period of year three through year ten of product
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Asset purchase agreement, percentage of royalties						19.00%
Journey \| Licensing Agreements \| Dr. Reddy's Laboratories, Ltd \| DFD Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees payment					$ 10,000
Journey \| Licensing Agreements \| Dr. Reddy's Laboratories, Ltd \| Payable on Net Sales of the DFD-29 Product
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones			$ 15,000	$ 3,000
Journey \| Licensing Agreements \| Minimum \| Dr. Reddy's Laboratories, Ltd \| Payable on Net Sales of the DFD-29 Product \| DFD Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sales royalties (as a percent)					10.00%
Journey \| Licensing Agreements \| Maximum \| Achievement of Certain Clinical Development, Regulatory and First Commercial Sale milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones					$ 150,000
Journey \| Licensing Agreements \| Maximum \| Dr. Reddy's Laboratories, Ltd \| Payable on Net Sales of the DFD-29 Product \| DFD Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sales royalties (as a percent)					14.00%
Ximino \| Licensing Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees payment								$ 2,400
Purchase of intangible asset								9,400
Ximino \| Licensing Agreements \| Achievement of Certain Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones								$ 7,000