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

Sponsored Research and Clinical Trial Agreements - Summary of Aevitas expense related to its sponsored research agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total Research and Development - Licenses Acquired	$ 458	$ 700	$ 2,278	$ 1,350
Research and clinical trial agreements [Member] \| Aevitas
Total Research and Development - Licenses Acquired	163	272	785	772
Research and clinical trial agreements [Member] \| Aevitas \| UMass - AAV [Member]
Total Research and Development - Licenses Acquired	163	0	218	0
Research and clinical trial agreements [Member] \| Aevitas \| UPenn - AAV [Member]
Total Research and Development - Licenses Acquired	0	255	567	755
Research and clinical trial agreements [Member] \| Aevitas \| Duke - AAV [Member]
Total Research and Development - Licenses Acquired	$ 0	$ 17	$ 0	$ 17