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

Debt and Interest - Long-term debt (Detail)

Debt and Interest - Long-term debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt [Line Items]
Total notes payable, long-term	$ 89,742	$ 84,406
Less: Discount of notes payable	5,086	4,903
Total notes payable	$ 84,656	79,503
Interest Rate	2.50%
IDB Note [Member]
Debt [Line Items]
Total notes payable, long-term	$ 14,929	14,929
Interest Rate	2.25%
2017 Subordinated Note Financing One [Member]
Debt [Line Items]
Total notes payable, long-term	$ 3,254	3,254
Interest Rate	8.00%
2017 Subordinated Note Financing Two [Member]
Debt [Line Items]
Total notes payable, long-term	$ 13,893	13,893
Interest Rate	8.00%
2017 Subordinated Note Financing Three [Member]
Debt [Line Items]
Total notes payable, long-term	$ 1,820	1,820
Interest Rate	8.00%
2017 Subordinated Note Financing Four [Member]
Debt [Line Items]
Total notes payable, long-term	$ 3,018	3,018
Interest Rate	8.00%
2017 Subordinated Note Financing Five [Member]
Debt [Line Items]
Total notes payable, long-term	$ 6,371	6,371
Interest Rate	8.00%
Opus Credit Facility [Member]
Debt [Line Items]
Total notes payable, long-term	$ 9,000	9,500
Interest Rate	12.00%
Caelum Convertible Note One [Member]
Debt [Line Items]
Total notes payable, long-term		1,000
Interest Rate	8.00%
Caelum Convertible Note Two [Member]
Debt [Line Items]
Total notes payable, long-term		6,800
Interest Rate	8.00%
Caelum Convertible Note Three [Member]
Debt [Line Items]
Total notes payable, long-term		2,114
Interest Rate	8.00%
Venture Notes One [Member]
Debt [Line Items]
Total notes payable, long-term	$ 6,517	6,517
Interest Rate	8.00%
Venture Notes Two [Member]
Debt [Line Items]
Total notes payable, long-term	$ 15,190	$ 15,190
Interest Rate	8.00%
Mustang 2019 Venture Debt [Member]
Debt [Line Items]
Total notes payable, long-term	$ 15,750
Interest Rate	9.00%
LIBOR Rate [Member]
Debt [Line Items]
Interest Rate	9.00%