REVENUE RECOGNITION - DISAGGREGATED REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 5,668	$ 8,743	$ 11,925	$ 13,865
Fixed fee license revenue
Disaggregation of Revenue [Line Items]
Revenues	1,292	4,254	2,578	5,994
Per-Unit royalty revenue
Disaggregation of Revenue [Line Items]
Revenues	4,301	4,414	9,197	7,721
Total royalty and license revenue
Disaggregation of Revenue [Line Items]
Revenues	5,593	8,668	11,775	13,715
Development, services, and other revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 75	$ 75	$ 150	$ 150

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration