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RESEARCH AND LICENSE AGREEMENTS WITH PRINCETON UNIVERSITY, UNIVERSITY OF SOUTHERN CALIFORNIA AND THE UNIVERSITY OF MICHIGAN - Additional Information (Details) - USD ($)
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Research and Development Arrangement, Contract to Perform for Others [Line Items]    
Royalty expense $ 112,000 $ 3,284,000
1997 Amended License Agreement [Member]    
Research and Development Arrangement, Contract to Perform for Others [Line Items]    
Royalty expense $ 112,000,000 3,300,000
Royalty rate for licensed products sold by the Company (in hundredths) 3.00%  
Royalty rate for licensed products sold by the Company's sublicenses (in hundredths) 3.00%  
2006 Research Agreement [Member]    
Research and Development Arrangement, Contract to Perform for Others [Line Items]    
Research agreement, extension term (in years) 2 years  
Research agreement, new amendment expiration date Apr. 30, 2023  
Maximum obligation $ 6,600,000  
Research and development expense incurred $ 285,000 $ 272,000