REVENUE RECOGNITION - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Oct. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) Radio_Frequencies	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) Radio_Frequencies	Sep. 30, 2019 USD ($)
Disaggregation of Revenue [Line Items]
Revenue from collaboration agreement		$ 604	$ 63	$ 1,148	$ 197
Proprietary Circuit Designs using XBAR Technology | Murata Manufacturing Co., Ltd.
Disaggregation of Revenue [Line Items]
Number of Licensed Specific Radio Frequencies | Radio_Frequencies			4		4
Prepaid royalties						$ 9,000
Written termination period				30 days
Contracted exclusivity period				30 months
Revenue from collaboration agreement	$ 2,000