Licenses Acquired - Additional Information (Detail)

v3.20.1

Licenses Acquired - Additional Information (Detail)																1 Months Ended										12 Months Ended
	Dec. 17, 2019 USD ($) Milestone agreement $ / shares shares	Aug. 23, 2019 USD ($)	Feb. 11, 2019 USD ($)	Aug. 02, 2018 USD ($)	Jul. 03, 2018 $ / shares shares	Jan. 03, 2018 USD ($)	Nov. 30, 2017 USD ($)	Nov. 20, 2017 USD ($)	Jul. 03, 2017 USD ($)	May 31, 2017 USD ($)	Apr. 25, 2017 USD ($)	Mar. 17, 2017 USD ($)	Oct. 15, 2015 USD ($)	Sep. 30, 2015 USD ($) shares	May 11, 2015 USD ($) $ / shares shares	Jun. 30, 2019 USD ($)	Nov. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Oct. 31, 2016 USD ($) shares	May 31, 2016 USD ($)	Apr. 30, 2015 USD ($)	Apr. 28, 2015 USD ($)	Mar. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Dec. 31, 2019 USD ($) installment	Dec. 31, 2018 USD ($)	Dec. 31, 2015 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration																										$ 2,400,000	$ 1,200,000
Research and Development in Process																										6,090,000	4,050,000
Payments for Fees							$ 100,000										$ 2,100,000
Stock Issued During Period, Shares, Issued for Services | shares														136,830
Stock Issued During Period, Value, Issued for Services														$ 600,000												500,000
Research and Development Expense																										81,326,000	87,383,000
Share Price | $ / shares					$ 3.04
Payment of Upfront Fees																										1,000,000
Revenue Recognition Milestone Method Payments Due																										14,500,000
Proceeds from Issuance of Common Stock			$ 13,100,000
Stock Issued During Period, Shares, New Issues | shares					164,473
Revenue from Contract with Customer, Including Assessed Tax																										34,921,000	23,376,000
Cost, Maintenance																										50,000	25,000
Dana Farber Cancer Institute [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual Maintenance Fee Payable														50,000
Collaborative Agreements with TGTX [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																$ 1,000,000										500,000
NeuPharma [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																								$ 1,000,000
NeuPharma [Member] | Collaborative Agreements with TGTX [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																										1,600,000	3,000,000
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 Milestone [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 (COH) [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees																							$ 2,000,000
UCLA MB-105 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due												$ 14,300,000
Tamid [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	$ 0
Dana Farber Cancer Institute [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Shares Issued, Price Per Share | $ / shares															$ 0.065
Stock Issued During Period, Shares, Issued for Services | shares															500,000
Stock Issued During Period, Value, Issued for Services															$ 32,500
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners																											5.00%
Proceeds from Issuance of Common Stock																											$ 10,000,000
Dana Farber Cancer Institute [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 Cancer Institute [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%
Annual Maintenance Fee Payable																								$ 1,000,000
Mustang Bio, Inc [Member] | Agreement With City Of Hope [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees								$ 300,000
Mustang Bio, Inc [Member] | Financial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																								14,500,000
Additional Minimum Annual Royalty Payable																								2,000,000
Cellvation Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees																										0	1,000
Teva Pharmaceutical Industries Ltd [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																												$ 500,000
Jubilant Biosys Ltd [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										$ 87,200,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners																										50.00%
Payment Of Upfront Licensing Fee																					$ 2,000,000
Jubilant Biosys Ltd [Member] | Sale Milestone [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] | 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 Milestones [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																					$ 89,000,000
Columbia University [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees																											300,000
Columbia University [Member] | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																			$ 5,500,000
Adimab, LLC Collaboration Agreement | Regulatory Approvals To Commercialize Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													$ 4,800,000
Adimab, LLC Collaboration Agreement | Clinical Development And Regulatory Milestones [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due													$ 7,100,000
License Agreement with NICHD | Cyprium [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Expense																										0	0
Payment of Upfront Fees																		$ 100,000
Revenue Recognition Milestone Method Payments Due																		15,000,000
License Agreement with NICHD | Cyprium [Member] | First Commercial Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																		1,000,000
License Agreement with NICHD | Cyprium [Member] | Clinical Development And Regulatory Milestones [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																		$ 1,700,000
License Agreement with NICHD | Cyprium [Member] | Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sales royalties (as a percent)																		15.00%
License Agreement with NICHD | Cyprium [Member] | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sales royalties (as a percent)																		20.00%
Spacer License with City of Hope
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	0
IV Tramadol [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment Of Upfront Licensing Fee																										3,000,000
Baergic[Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of license agreement | agreement	2
AZ License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of Upfront Fees	$ 75,000,000
Cincinnati License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment Of Upfront Licensing Fee	$ 6,500,000
Pentameter [Member] | City of Hope (COH) [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum Annual Royalty Payable																						$ 750,000
Pentameter [Member] | City of Hope (COH) [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 (COH) [Member] | Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																						26,000,000
Royalty [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from Contract with Customer, Including Assessed Tax																										100,000	400,000
Checkpoint [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	1,000,000
Checkpoint [Member] | Collaborative Agreements with TGTX [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										9,400,000
Checkpoint [Member] | First Commercial Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										28,600,000
Checkpoint [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 [Member] | Regulatory Filings And Commercial Sales In Specified Territories [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										19,200,000
Mustang [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										1,350,000	1,275,000
Mustang [Member] | Financial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due											$ 200,000
Mustang [Member] | Nationwide Children's Hospital License Agreement (MB-108)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																										200,000
Revenue Recognition Milestone Method Payments Due																										152,800,000
Mustang [Member] | CSL Behring Licence MB-107
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Expense																										200,000
Payment of Upfront Fees		$ 200,000
Revenue Recognition Milestone Method Payments Due		$ 1,200,000
Helocyte [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										450,000	1,521,000
Payments For Research And Development Expenses																										0	1,500,000
Helocyte [Member] | License Agreement with NIAD
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										500,000	0
Payment of Upfront Fees																										500,000
Minimum Annual Royalty Payable																										55,000
Additional Minimum Annual Royalty Payable																										$ 1,050,000
Payment Of Upfront Fees, Number Of Installments | installment																										3
Helocyte [Member] | Triplex [Member] | Development Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																											26,000,000
Helocyte [Member] | Triplex [Member] | Sale Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																											3,700,000
Helocyte [Member] | Triplex [Member] | Financial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																											7,500,000
Caelum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										$ 0	252,000
Licensing Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration																						$ 45,000
Licensing Agreements [Member] | Dana Farber Cancer Institute [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																											1,000,000
Licensing Agreements [Member] | Cellvation Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Shares, Issued for Services | shares																				500,000
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 Milestone [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
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
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Additional Minimum Annual Royalty Payable																				200,000
Licensing Agreements [Member] | IV Tramadol [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments for Fees																									$ 3,000,000
Licensing Agreements [Member] | AZ License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Shares, Issued for Services | shares	2,492,192
Percentage of common shares issued (in percent)	19.95%
Payment of Upfront Fees	$ 3,000,000
Revenue Recognition Milestone Method Payments Due	$ 130,000,000
Number of net sales milestones | Milestone	3
Licensing Agreements [Member] | AZ License [Member] | Valuation Technique, Discounted Cash Flow [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percentage of lack of marketability	44.60%
Percentage of weighted average cost of capital	20.50%
Net of debt in per share | $ / shares	$ 0.029
Amount of net of debt utilized	$ 100,000
Licensing Agreements [Member] | AZ License [Member] | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuance of anti-dilution protection of shares	$ 75,000,000
Licensing Agreements [Member] | Cincinnati License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock Issued During Period, Shares, Issued for Services | shares	624,922
Percentage of common shares issued (in percent)	5.00%
Payment of Upfront Fees	$ 200,000
Reimbursement of past patent expenses	30,000
Revenue Recognition Milestone Method Payments Due	$ 21,000,000
Number of net sales milestones | Milestone	4
Licensing Agreements [Member] | Cincinnati License [Member] | Valuation Technique, Discounted Cash Flow [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percentage of lack of marketability	44.60%
Percentage of weighted average cost of capital	20.50%
Net of debt in per share | $ / shares	$ 0.029
Amount of net of debt utilized	$ 100,000
Licensing Agreements [Member] | Cincinnati License [Member] | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuance of anti-dilution protection of shares	$ 15,000,000
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
AR CD123 License [Member] | City of Hope (COH) [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										300,000	0
Revenue Recognition Milestone Method Payments Due																										14,500,000
AR IL-13 License [Member] | City of Hope (COH) [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										14,500,000
HER2 Technology License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	200,000
Payment of Upfront Fees										$ 600,000
Revenue Recognition Milestone Method Payments Due										14,900,000
Annual Maintenance Fee Payable										50,000
CS1 License [Member] | Mustang [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										200,000	0
Payment of Upfront Fees									$ 600,000
Revenue Recognition Milestone Method Payments Due										14,900,000
Annual Maintenance Fee Payable										50,000
PSCA [Member] | Mustang [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										200,000	0
Payment of Upfront Fees									300,000
Revenue Recognition Milestone Method Payments Due										14,900,000
Annual Maintenance Fee Payable										$ 50,000
University of California [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										300,000	0
Fred Hutchinson Cancer Research Center License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	0
Payment of Upfront Fees									300,000
Revenue Recognition Milestone Method Payments Due									39,100,000
Annual Maintenance Fee Payable									$ 50,000
Harvard College License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	0
Revenue Recognition, Sales and Marketing Milestone Method Payments Due																										16,700,000
CITY OF HOPE IV ICV License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	0
Payment of Upfront Fees																		$ 100,000
Revenue Recognition Milestone Method Payments Due																		$ 100,000
CITY OF HOPE IV ICV License [Member] | Mustang [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																								$ 200,000
City of Hope MB-101 (IL13R2 CAR T for Glioblastoma) [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	0
Manufacturing License [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration						$ 75,000
Research and Development in Process																											100,000
St Jude Childrens Research Hospital [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process																										0	$ 1,000,000
Revenue Recognition Milestone Method Payments Due				$ 13,500,000
Additional Annual License fee				100,000
Annual license fee				$ 1,000,000
Anti - GTR License [Member] | Checkpoint [Member] | Collaborative Agreements with TGTX [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue Recognition Milestone Method Payments Due																										21,500,000
Anti - GTR License [Member] | Checkpoint [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
Anti - GTR License [Member] | Checkpoint [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