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

Fair Value Measurements - Changes in Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	$ 4,160	$ 0
Purchases		3,218
Change in fair value of investment	(1,675)	942
Balance	2,485	4,160
CB Pharma Acquisitions Corp [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	3,910	0
Purchases		2,675
Change in fair value of investment	(1,675)	1,235
Balance	2,235	3,910
Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	0	0
Purchases		293
Change in fair value of investment	0	(293)
Balance	0	0
Other Long-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	250	0
Purchases		250
Change in fair value of investment	0
Balance	$ 250	$ 250