REVENUE RECOGNITION - DISAGGREGATED REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 11,010	$ 5,668	$ 18,169	$ 11,925
Fixed fee license revenue
Disaggregation of Revenue [Line Items]
Revenues	1,824	1,292	3,099	2,578
Per-unit royalty revenue
Disaggregation of Revenue [Line Items]
Revenues	9,057	4,301	14,850	9,197
Total royalty and license revenue
Disaggregation of Revenue [Line Items]
Revenues	10,881	5,593	17,949	11,775
Development, services, and other revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 129	$ 75	$ 220	$ 150