Annual report pursuant to Section 13 and 15(d)

License, Clinical Trial and Sponsored Research Agreements (Other - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)

v3.21.1
License, Clinical Trial and Sponsored Research Agreements (Other - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details) - USD ($)
 1 Months Ended 12 Months Ended
Mar. 17, 2018
Nov. 28, 2017
Jul. 03, 2017
Nov. 30, 2020
Jun. 30, 2020
Dec. 31, 2019
Dec. 31, 2020
Dec. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Research and development expense             $ 37,237,000 $ 30,042,000
Sponsored Research and Clinical Trial Agreements [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Research and development expense             7,717,000 6,143,000
Beth Israel Deaconess Medical Center - CRISPR | Sponsored Research and Clinical Trial Agreements [Member] | CRISPR [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Milestones payable   $ 800,000            
Research and development expense             0 69,000
Agreement term   3 years            
Fred Hutchinson Cancer Research Center [Member] | Sponsored Research and Clinical Trial Agreements [Member] | CD20 Product or Process [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Milestones payable     $ 5,300,000          
Additional milestone payments       $ 800,000        
Research and development expense             1,804,000 762,000
Fred Hutchinson Cancer Research Center [Member] | Sponsored Research and Clinical Trial Agreements [Member] | Manufacturing [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Milestones payable $ 600,000              
Research and development expense             0 200,000
Fred Hutchinson Cancer Research Center [Member] | Clinical Trial Agreements [Member] | CD20 Product or Process [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Research and development expense             1,800,000 600,000
St. Jude Children's Research Hospital [Member] | Sponsored Research and Clinical Trial Agreements [Member] | ST. Jude - XSCID [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Milestones payable           $ 800,000    
Research and development expense             1,842,000 777,000
St. Jude Children's Research Hospital [Member] | Data Transfer Agreement [Member] | ST. Jude - XSCID [Member]                
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                
Upfront fees paid         $ 1,100,000      
Research and development expense             $ 1,800,000 $ 0