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

Sponsored Research and Clinical Trial Agreements - Summary of Mustang expense related to its sponsored research agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Total licenses acquired expense	$ 700	$ 3,706	$ 1,350	$ 3,804
Mustang [Member]
Total licenses acquired expense	700	1,000	1,350	1,075
Research and clinical trial agreements [Member] \| Mustang [Member]
Total licenses acquired expense	1,176	1,407	4,441	4,087
Research and clinical trial agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member]
Total licenses acquired expense	500	500	1,500	1,500
Research and clinical trial agreements [Member] \| Mustang [Member] \| COH - CD123 (MB-102) [Member]
Total licenses acquired expense	269	123	1,028	387
Research and clinical trial agreements [Member] \| Mustang [Member] \| COH - IL13Ra2 (MB-101) [Member]
Total licenses acquired expense	244	346	811	849
Research and clinical trial agreements [Member] \| Mustang [Member] \| City of Hope - Manufacturing [Member]
Total licenses acquired expense	114	114	343	344
Research and clinical trial agreements [Member] \| Mustang [Member] \| Fred Hutch-CD20 (MB-106) [Member]
Total licenses acquired expense	$ 49	255	690	938
Research and clinical trial agreements [Member] \| Mustang [Member] \| BIDMC - CRISPR [Member]
Total licenses acquired expense		$ 69	$ 69	$ 69