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

Segment Information - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Customer One [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Gross	$ 4.2	$ 0.3	$ 5.3	$ 0.6
Accounts Receivable, Net	2.1		2.1		$ 1.1
Customer Two [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Gross	2.2	0.3	3.8	0.3
Accounts Receivable, Net	$ 0.7		$ 0.7		$ 0.5
Customer Three [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Gross		$ 0.3		$ 0.3