Licenses Acquired - Additional Information (Detail)

v3.6.0.2

Licenses Acquired - Additional Information (Detail) - USD ($)			1 Months Ended												3 Months Ended	12 Months Ended
		May 11, 2015	Oct. 31, 2016	Sep. 30, 2016	May 31, 2016	Feb. 23, 2016	Dec. 31, 2015	Oct. 31, 2015	Sep. 30, 2015	Jul. 16, 2015	Jun. 17, 2015	Apr. 28, 2015	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 01, 2016	Jul. 31, 2016	Jun. 01, 2016	Feb. 17, 2015
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments to Acquire Intangible Assets																$ 350,000	$ 1,250,000	$ 0
Research And Development In Process																5,532,000	11,408,000	0
Stock Issued During Period, Shares, Issued for Services						10,000
Stock Issued During Period, Value, Issued for Services																2,000	1,000	4,000
Research And Development Expense																(35,134,000)	(29,810,000)
Payments to Acquire in Process Research and Development																200,000
Share Price																			$ 2.39		$ 2.82
Stock Issued During Period, Value, Other																		3,502,000
Proceeds From Issuance Of Common Stock																0	0	3,502,000
Share-based Compensation																$ 12,128,000	$ 14,291,000	5,546,000
Common Stock Shares Authorized							100,000,000								100,000,000	100,000,000	100,000,000
Common Stock [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Shares, Issued for Services			500,000
Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due										$ 22,000,000				$ 10,700,000
Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due										7,000,000				26,200,000
NeuPharma [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research And Development In Process													$ 1,000,000			$ 1,000,000
NeuPharma [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													40,000,000
NeuPharma [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													40,000,000
NeuPharma [Member] | Regulatory Approvals To Commercialize Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													$ 22,500,000
City Of Hope [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Marketability Percentage Of Invested Capital													44.80%
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent													30.00%
Share Price													$ 0.147
Stock Issued During Period, Value, Other													$ 100,000
City Of Hope [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												$ 1,500,000
City Of Hope [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												13,000,000
National Institutes of Health [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Milestone Fees										700,000
New Zealand Pharmaceuticals Ltd [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Reimbursement Revenue										600,000
Dana-Farber [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Shares Issued, Price Per Share		$ 0.065
Stock Issued During Period, Shares, Issued for Services		500,000							136,830
Stock Issued During Period, Value, Issued for Services		$ 32,500							$ 600,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners															5.00%	5.00%
Proceeds From Issuance Of Common Stock																$ 10,000,000
Dana-Farber [Member] | First Commercial Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									21,500,000
Dana-Farber [Member] | Additional Sales Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									60,000,000
Mustang Bio, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty Guarantees, Commitments, Amount													$ 1,000,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners													10.00%
Minimum Annual Royalty Payable													$ 1,000,000
Mustang Bio, Inc [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													14,500,000
Mustang Bio, Inc [Member] | Financial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													2,000,000
Escala Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees										$ 1,300,000
Reimbursement Revenue																	$ 1,300,000
Gene Medicine, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																19,300,000
Royalty Guarantees, Commitments, Amount			$ 100,000																	$ 300,000
Effcon Laboratories, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees				$ 200,000
Revenue Recognition Milestone Method Payments Due				5,300,000
Royalty Guarantees, Commitments, Amount				$ 1,600,000
Teva Pharmaceutical Industries Ltd [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees							$ 500,000
Teva Pharmaceutical Industries Ltd [Member] | Regulatory Approvals To Commercialize Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due							206,500,000
Teva Pharmaceutical Industries Ltd [Member] | Clinical Development and Regulatory Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due							$ 220,000,000
Jubilant Biosys Ltd [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research And Development In Process																2,000,000
Revenue Recognition Milestone Method Payments Due																$ 87,500,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners															50.00%	50.00%
Payment Of Upfront Licensing Fee					$ 2,000,000
Royalty Revenue																$ 1,500,000
Jubilant Biosys Ltd [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone Method Revenue Additional Payments Eligible To Receive					89,000,000
Jubilant Biosys Ltd [Member] | Regulatory Approvals To Commercialize Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due					59,500,000
Jubilant Biosys Ltd [Member] | Successful Achievement Of One Preclinical Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																300,000
Jubilant Biosys Ltd [Member] | Completion Of Three Clinical Development Milestones For Two Licensed Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																25,500,000
Jubilant Biosys Ltd [Member] | Five Regulatory Approvals And First Commercial Sales [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																61,700,000
Jubilant Biosys Ltd [Member] | Three Sales Milestones Based On Aggregate Net Sales [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																89,000,000
Jubilant Biosys Ltd [Member] | Clinical Development and Regulatory Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due					$ 89,000,000
Jubilant Biosys Ltd [Member] | TG Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment Of Upfront Licensing Fee																1,000,000
Collaborative Agreements with TGTX [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees									500,000							600,000	600,000
Collaborative Agreements with TGTX [Member] | NeuPharma [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																42,000
Agreement With City Of Hope [Member] | Mustang Bio, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment Of Upfront Licensing Fee													2,000,000
Triplex [Member] | City Of Hope [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum Annual Royalty Payable												750,000
Pentameter [Member] | City Of Hope [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum Annual Royalty Payable												750,000
Pentameter [Member] | City Of Hope [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												5,500,000
Pentameter [Member] | City Of Hope [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												26,000,000
Coronado SO Co, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research And Development In Process																$ 0	$ 1,607,000	0
Payments for Fees														$ 900,000
Stock Issued During Period, Shares, Other														150,000
Research And Development Expense								$ 500,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners							13.00%								13.00%	13.00%	13.00%
Checkpoint Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research And Development In Process																$ 3,160,000	$ 3,159,000	0
Stock Issued During Period, Value, Purchase of Assets																$ 22,000,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	[1]						62.30%								62.90%	62.90%	62.30%
Checkpoint Therapeutics, Inc [Member] | First Commercial Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									21,500,000
Checkpoint Therapeutics, Inc [Member] | Additional Sales Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									60,000,000
Checkpoint Therapeutics, Inc [Member] | Clinical Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									7,000,000
Checkpoint Therapeutics, Inc [Member] | Commercial Sales In Specified Territories [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due									$ 14,500,000
Checkpoint Therapeutics, Inc [Member] | Dana-Farber [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Value, Purchase of Assets																$ 5,500,000
Helocyte [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research And Development In Process												200,000				$ 53,000	$ 200,000	$ 0
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners															20.50%	20.50%
Helocyte [Member] | Triplex [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												9,000,000
Helocyte [Member] | Triplex [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												26,000,000
Licensing Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments to Acquire Intangible Assets												$ 45,000	$ 150,000
Licensing Agreements [Member] | City Of Hope [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Marketability Percentage Of Invested Capital																44.50%
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent																30.00%
Share Price															$ 0.097	$ 0.097
Stock Issued During Period, Value, Other																$ 48,500
Licensing Agreements [Member] | City Of Hope [Member] | Common Class A [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued					500,000
Licensing Agreements [Member] | Dana-Farber [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																	$ 1,000,000
Licensing Agreements [Member] | Mustang Bio, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Shares, Issued for Services															293,588
Stock Issued During Period, Value, Issued for Services															$ 1,700,000
Share Price															$ 5.73	$ 5.73
Proceeds from Third Party Investors															$ 10,000,000
Common Stock Shares Authorized															1,000,000	1,000,000
Licensing Agreements [Member] | Cellvation Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Marketability Percentage Of Invested Capital			40.20%
Stock Issued During Period, Shares, Issued for Services			500,000
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent			30.00%
Share Price			$ 0.024
Stock Issued During Period, Value, Other			$ 12,000
Payment of Upfront Fees			$ 300,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			5.00%
Licensing Agreements [Member] | Cellvation Inc [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due			$ 6,200,000
Licensing Agreements [Member] | Cellvation Inc [Member] | Sale Millstone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due			6,000,000
Licensing Agreements [Member] | Cellvation Inc [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Additional Minimum Annual Royalty Payable			50,000
Licensing Agreements [Member] | Cellvation Inc [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Additional Minimum Annual Royalty Payable			200,000
Licensing Agreements [Member] | Cellvation Inc [Member] | Research and Development - Licenses Acquired [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Share-based Compensation																$ 12,000
Licensing Agreements [Member] | Coronado SO [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Marketability Percentage Of Invested Capital																44.80%
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent																30.00%
Share Price															$ 1.19	$ 1.19
Licensing Agreements [Member] | IV Tramadol [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments to Acquire Intangible Assets											$ 1,000,000
Payments for Fees														$ 2,000,000
Licensing Agreements [Member] | Helocyte [Member] | Common Class A [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued					8,333
Avenue Therapeutics, Inc. [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Shares Issued, Price Per Share							$ 0.146										$ 0.146
Research And Development Expense																$ 14,000	$ 29,000
Debt Instrument, Fee Amount																						$ 3,000,000
Secondary License [Member] | Cellvation Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees			50,000
Revenue Recognition Milestone Method Payments Due			300,000
Second TBI License [Member] | Cellvation Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum Annual Royalty Payable			$ 100,000
[1] Checkpoint is consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Checkpoint’s Class A Common Shares which provide super-majority voting rights.