Annual report pursuant to Section 13 and 15(d)

Licenses Acquired (Schedule of Research and Development for Licenses Acquired) (Details)

v3.21.1
Licenses Acquired (Schedule of Research and Development for Licenses Acquired) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired $ 2,834 $ 6,090  
Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 2,489 1,350  
Licensing Agreements [Member] | Mustang [Member] | Spacer [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 2,489 1,350  
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 334 0  
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member] | MB-102 (CD 123 CAR T for AML) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 334 250 $ 0
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member] | MB-101 (IL13R2 CAR T for Glioblastoma) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 334 0  
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member] | MB-103 (HER2 CAR T) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 500 0  
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member] | MB-104 (CS1 CAR T) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 200 200  
Licensing Agreements [Member] | City of Hope (COH) [Member] | Mustang [Member] | MB-105 (PSCA CAR T) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 200 200  
Licensing Agreements [Member] | Fred Hutchinson Cancer Research Center [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 300 0  
Licensing Agreements [Member] | Nationwide Children's Hospital [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 0 200  
Licensing Agreements [Member] | Nationwide Children's Hospital [Member] | Mustang [Member] | MB-108 (C134 Oncolytic Virus for GBM [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired   200  
Licensing Agreements [Member] | CSL Behring [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 170 200  
Licensing Agreements [Member] | CSL Behring [Member] | Mustang [Member] | MB-107 (XSCID) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 200 200  
Licensing Agreements [Member] | University of California [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 0 300  
Licensing Agreements [Member] | University of California [Member] | Mustang [Member] | MB-105 (PSCA CAR T) [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired 200 0  
Licensing Agreements [Member] | SIRION Biotech [Member] | Mustang [Member]      
Research and Development Arrangement, Contract to Perform for Others [Line Items]      
Research and development - licenses acquired $ 117 $ 0