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

Quarterly report [Sections 13 or 15(d)]

License Agreements (Journey and Other Narrative) (Details)

License Agreements (Journey and Other Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended		12 Months Ended
	Apr. 24, 2025	Feb. 28, 2023	Apr. 30, 2024	Jun. 30, 2021	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development - licenses acquired					$ 0	$ 0
Product revenue, net					13,139	$ 13,030
Journey \| Licensing Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Product revenue, net					$ 2,100
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			$ 3,000				$ 15,000
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%
Avenue \| AnnJi Pharmaceutical Co
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty expense		$ 3,000
Avenue \| AnnJi Pharmaceutical Co \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Termination date	48 months
Repurchase of shares	$ 1
Legal expense reimbursed	$ 200
Percentage of royalty on future net sales	1.75%
Percentage to be received on third party licensing revenue	15.00%
Maximum amounts to be received on third party licensing revenue	$ 7,500
Minimum amounts to be received on New Drug Application	4,000
Avenue \| AnnJi Pharmaceutical Co \| Achievement of Certain Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones		165,000
Avenue \| AnnJi Pharmaceutical Co \| Drug development milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees payment		27,500
Avenue \| AnnJi Pharmaceutical Co \| Due over the next ninety days \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment agreement	2,000
Avenue \| AnnJi Pharmaceutical Co \| Due within thirty days \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment agreement	1,000
Avenue \| AnnJi Pharmaceutical Co \| Due within ninety days \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment agreement	1,000
Avenue \| AnnJi Pharmaceutical Co \| Upon The Occurrence Of Certain Development And Regulatory Milestone Events Pertaining To Aj201 \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments receivable	5,000
Avenue \| AnnJi Pharmaceutical Co \| Upon Aj201 Experiencing Certain Commercial Sales Milestone Events \| Subsequent events
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments receivable	$ 17,000
Avenue \| Minimum \| AnnJi Pharmaceutical Co \| Achievement of Certain Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net sales milestones		75,000
Avenue \| Maximum \| AnnJi Pharmaceutical Co \| Achievement of Certain Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net sales milestones		750,000
Avenue \| Maximum \| AnnJi Pharmaceutical Co \| First Indication Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones		10,800
Avenue \| Maximum \| AnnJi Pharmaceutical Co \| Additional Indication Milestones \| DFD Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments of milestones		$ 14,500