REVENUE RECOGNITION - DISAGGREGATED REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 7,159	$ 6,257
Fixed fee license revenue
Disaggregation of Revenue [Line Items]
Revenues	1,275	1,287
Per-unit royalty revenue
Disaggregation of Revenue [Line Items]
Revenues	5,793	4,895
Total royalty and license revenue
Disaggregation of Revenue [Line Items]
Revenues	7,068	6,182
Development, services, and other revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 91	$ 75