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

Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Marketable securities, Amortized Cost	$ 20,002us-gaap_TradingSecuritiesCost
Marketable securities, Unrealized Gain	0
Marketable securities, Unrealized Loss	0
Trading Securities	20,002us-gaap_TradingSecurities
U.S. treasury bill
Marketable securities, Amortized Cost	19,998
Marketable securities, Unrealized Gain	0
Marketable securities, Unrealized Loss	0
Trading Securities	19,998
Mutual fund
Marketable securities, Amortized Cost	4
Marketable securities, Unrealized Gain	0
Marketable securities, Unrealized Loss	0
Trading Securities	$ 4