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

Net Loss Per Common Share - Computations of Diluted Weighted Average Shares Outstanding (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	9,679,623	9,188,360	9,555,712	8,749,229
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	685,061	692,916	685,061	702,353
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	2,071,032	2,187,076	2,114,126	2,384,348
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	6,912,530	6,308,368	6,749,641	5,662,528
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	11,000	0	6,884	0