RESEARCH AND LICENSE AGREEMENTS WITH PRINCETON UNIVERSITY, UNIVERSITY OF SOUTHERN CALIFORNIA AND THE UNIVERSITY OF MICHIGAN - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty expense	$ 149,000	$ 1,618,000	$ 261,000	$ 4,902,000
1997 Amended License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty expense	149,000	1,600,000	$ 261,000	4,900,000
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	4,900,000		$ 4,900,000
Research and development expense incurred	$ 394,000	$ 304,000	$ 679,000	$ 581,000