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

Stockholders' Equity (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Stockholders' Equity
Total stock-based compensation expense	$ 2,149	$ 3,197	$ 6,782	$ 26,280
Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost
Stockholders' Equity
Total stock-based compensation expense	31	152	89	6,245
Location, Statement of Income, Balance [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense
Stockholders' Equity
Total stock-based compensation expense	2,118	3,045	6,693	20,035
Employee and non-employee awards
Stockholders' Equity
Total stock-based compensation expense	665	990	2,432	6,514
Executive awards
Stockholders' Equity
Total stock-based compensation expense	102	167	369	527
Avenue
Stockholders' Equity
Total stock-based compensation expense	47	163	169	523
Checkpoint
Stockholders' Equity
Total stock-based compensation expense				14,097
Mustang
Stockholders' Equity
Total stock-based compensation expense	2	23	45	106
Journey
Stockholders' Equity
Total stock-based compensation expense	$ 1,333	$ 1,854	3,759	$ 4,513
Other
Stockholders' Equity
Total stock-based compensation expense			$ 8