Fortress Biotech, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Detail)

Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015	Apr. 30, 2013 sqft	Jul. 31, 2012 sqft
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense		$ 2,700,000us-gaap_LeaseAndRentalExpense
Operating Leases, Rent Expense, Net, Total			354,000us-gaap_OperatingLeasesRentExpenseNet	284,000us-gaap_OperatingLeasesRentExpenseNet	93,000us-gaap_OperatingLeasesRentExpenseNet
Reorganization Value, Net Realizable Value of Asset Dispositions	100,000	100,000	100,000
Lease Termination Period	2016 - 2015
Stock Issued During Period, Value, Stock Options Exercised			596,000	970,000
Subsequent Event [Member]
Operating Leased Assets [Line Items]
Stock Issued During Period, Value, Stock Options Exercised						82,000
Research and Development Expense [Member]
Operating Leased Assets [Line Items]
Disposal Group, Including Discontinued Operation, Operating Expense			700,000
Woburn, MA facility [Member]
Operating Leased Assets [Line Items]
Disposal Group, Including Discontinued Operation, Operating Expense			700,000
Operating Leases, Future Minimum Payments, Remainder of Fiscal Year	300,000	300,000	300,000
Reorganization Value, Net Realizable Value of Asset Dispositions	400,000	400,000	400,000
New York, NY office space [Member]
Operating Leased Assets [Line Items]
Operating Leases, Income Statement, Sublease Revenue			100,000
Opus Point Partners Management, LLC [Member]
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense		500,000
Percentage of Rentable Area		20.00%
Prepaid Rent	199,000	199,000	199,000
TG Therapeutics, Inc [Member]
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense		1,100,000
Percentage of Rentable Area		40.00%
Journey Medical Corporation [Member]
Operating Leased Assets [Line Items]
Land Subject to Ground Leases	2,295	2,295	2,295
Operating Leases, Rent Expense, Net, Total			39,000
Lease Agreements [Member]
Operating Leased Assets [Line Items]
Land Subject to Ground Leases					8,700		1,500	3,200
Operating Leases, Rent Expense					118,000		122,000	94,000
Operating Leases, Rent Expense, Net, Total					590,000
Contracted Build Out Costs Associated With Lease				$ 373,000