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

Related Party Transactions (Management Services Agreement) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($)
Related Party Transaction [Line Items]
Fortress - MSA Income	$ (4,500)
Helocyte [Member]
Related Party Transaction [Line Items]
Effective date	Mar. 20, 2015
Consolidated (income) expense	$ 500
Avenue [Member]
Related Party Transaction [Line Items]
Effective date	Feb. 17, 2015
Mustang [Member]
Related Party Transaction [Line Items]
Effective date	Mar. 13, 2015
Consolidated (income) expense	$ 500
Checkpoint [Member]
Related Party Transaction [Line Items]
Effective date	Mar. 17, 2015
Consolidated (income) expense	$ 500
Cellvation [Member]
Related Party Transaction [Line Items]
Effective date	Oct. 31, 2016
Consolidated (income) expense	$ 500
Baergic [Member]
Related Party Transaction [Line Items]
Effective date	Mar. 09, 2017
Consolidated (income) expense	$ 500
Cyprium [Member]
Related Party Transaction [Line Items]
Effective date	Mar. 13, 2017
Consolidated (income) expense	$ 500
Aevitas [Member]
Related Party Transaction [Line Items]
Effective date	Jul. 28, 2017
Consolidated (income) expense	$ 500
Oncogenuity [Member]
Related Party Transaction [Line Items]
Effective date	Feb. 10, 2017
Consolidated (income) expense	$ 500
FBIO Acquisition Corp VIII [Member]
Related Party Transaction [Line Items]
Effective date	Nov. 07, 2017
Consolidated (income) expense	$ 500