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

Fair Value Measurements - Warrant Liabilities And Convertible Notes At Fair Value (Detail) - Helocyte [Member]	3 Months Ended	9 Months Ended
	Sep. 30, 2016 $ / shares	Sep. 30, 2016 $ / shares
Convertible Debt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	0.64%
Expected dividend yield	0.00%
Probability of conversion	0.15%
Convertible Debt [Member] \| Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected term in years		1 year 6 months
Expected volatility		63.30%
Convertible Debt [Member] \| Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected term in years		1 year 3 months
Expected volatility		60.00%
Warrant [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	0.64%
Expected dividend yield	0.00%
Strike price	$ 0.15	$ 0.15
Warrant [Member] \| Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected term in years		1 year 6 months
Expected volatility		63.30%
Warrant [Member] \| Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected term in years		1 year 3 months
Expected volatility		60.00%