REVENUE RECOGNITION - NARRATIVE (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized, true up	$ 234	$ 149	$ (326)
Fixed fee license revenue recognized				$ 2,300
Fixed fee license revenue | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, payment terms				30 days
Fixed fee license revenue | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, payment terms				45 days
Per-unit royalty revenue | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, payment terms				30 days
Per-unit royalty revenue | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, payment terms				60 days