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

Sponsored Research and Clinical Trial Agreements (Narrative) (Details)

Sponsored Research and Clinical Trial Agreements (Narrative) (Details)		1 Months Ended						3 Months Ended		9 Months Ended
	Jul. 01, 2020 USD ($)	Oct. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	May 31, 2020 USD ($)	Feb. 28, 2017 USD ($)	Mar. 31, 2015 USD ($) installment	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2021 USD ($)	Nov. 30, 2020 USD ($)	Jul. 03, 2017 USD ($)
Research and development								$ 27,367,000	$ 13,298,000	$ 70,226,000	$ 43,868,000
Research and Clinical Trial Agreements [Member] \| Aevitas [Member]
Research and development								17,000	163,000	289,000	785,000
Research and Clinical Trial Agreements [Member] \| Aevitas [Member] \| University of Massachusetts [Member]
Research and development								17,000	163,000	289,000	218,000
Research and Clinical Trial Agreements [Member] \| Aevitas [Member] \| University of Pennsylvania [Member]
Research and development								0	0	0	567,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member]
Research and development								1,756,000	734,000	4,858,000	4,900,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member]
Research and development								0	0	0	500,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-102 (CD 123 CAR T for AML) [Member]
Research and development								24,000	48,000	250,000	344,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-104 (CS1 CAR T) [Member]
Research and development								138,000	65,000	510,000	835,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-101 (IL13R2 CAR T for Glioblastoma) [Member]
Research and development								199,000	96,000	992,000	422,000
Sponsored research agreement, funding commitment							$ 2,000,000.0
Number of installments to pay the upfront fees \| installment							4
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-103 (HER2 CAR T) [Member]
Research and development								319,000	0	473,000	0
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-105 (PSCA CAR T) [Member]
Research and development									0	69,000	0
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| Fred Hutchinson Cancer Research Center [Member] \| MB-106 (CD20 CAR T) [Member]
Research and development								492,000	418,000	1,490,000	1,134,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| St. Jude Children's Research Hospital [Member] \| MB-107 (XSCID) [Member]
Research and development								330,000	107,000	610,000	1,665,000
Research and Clinical Trial Agreements [Member] \| Mustang [Member] \| Mayo Clinic [Member]
Research and development								231,000	0	464,000	0
Research and Clinical Trial Agreements [Member] \| Oncogenuity [Member]
Research and development								334,000	125,000	1,005,000	250,000
Research and Clinical Trial Agreements [Member] \| Oncogenuity [Member] \| Columbia University [Member]
Research and development								187,000	125,000	562,000	250,000
Funding commitment period					5 years
Research and Clinical Trial Agreements [Member] \| Oncogenuity [Member] \| University of California [Member]
Research and development								56,000	0	178,000	0
Research and Clinical Trial Agreements [Member] \| Oncogenuity [Member] \| University of Oxford [Member]
Research and development								91,000	0	265,000	0
Research and Clinical Trial Agreements [Member] \| Oncogenuity [Member] \| Maximum [Member] \| Columbia University [Member]
Sponsored research agreement, funding commitment					$ 4,800,000
Sponsored Research Agreement [Member] \| Mustang [Member] \| City of Hope (COH) [Member]
Research and development										0	500,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-102 (CD 123 CAR T for AML) [Member]
Research and development								24,000	48,000	300,000	300,000
Upfront fees payment						$ 19,450
Sponsored research agreement, funding commitment						$ 200,000
Funding commitment period						3 years
Sponsored research agreement, additional funding commitment						$ 97,490
Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-104 (CS1 CAR T) [Member]
Research and development								100,000	100,000	500,000	800,000
Upfront fees payment				$ 800,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-101 (IL13R2 CAR T for Glioblastoma) [Member]
Research and development								200,000	100,000	1,000,000.0	400,000
Upfront fees payment		$ 29,000				9,300
Payments of milestones						$ 100,000
Sponsored research agreement, funding commitment		100,000										$ 200,000
Funding commitment period						3 years
Sponsored research agreement, additional funding commitment		200,000				$ 200,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-103 (HER2 CAR T) [Member]
Research and development								300,000		500,000
Upfront fees payment			$ 29,375
Clinical Trial Agreements [Member] \| Mustang [Member] \| City of Hope (COH) [Member] \| MB-105 (PSCA CAR T) [Member]
Research and development								23,000	0	100,000	0
Upfront fees payment		33,000
Sponsored research agreement, funding commitment		$ 2,300,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| Fred Hutchinson Cancer Research Center [Member] \| MB-106 (CD20 CAR T) [Member]
Research and development								500,000	400,000	1,500,000	1,100,000
Sponsored research agreement, funding commitment														$ 5,300,000
Sponsored research agreement, additional funding commitment													$ 800,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| St. Jude Children's Research Hospital [Member] \| MB-107 (XSCID) [Member]
Research and development								300,000	100,000	600,000	1,700,000
Upfront fees payment	$ 1,100,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| Mayo Clinic [Member]
Research and development								200,000		500,000
Sponsored research agreement, funding commitment								$ 2,100,000		$ 2,100,000
Funding commitment period										2 years
Clinical Trial Agreements [Member] \| Mustang [Member] \| Maximum [Member] \| City of Hope (COH) [Member] \| MB-104 (CS1 CAR T) [Member]
Sponsored research agreement, funding commitment				$ 2,400,000
Clinical Trial Agreements [Member] \| Mustang [Member] \| Maximum [Member] \| City of Hope (COH) [Member] \| MB-103 (HER2 CAR T) [Member]
Sponsored research agreement, funding commitment			$ 3,000,000.0						$ 3,000,000.0		$ 3,000,000.0