REVENUE RECOGNITION - Schedule of Changes in Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Contract assets
Contract assets, beginning	$ 0	$ 36
Contract assets at beginning of year transferred to accounts receivable	0	(36)
Reversal of contract assets due to changes in transaction price	0	(8)
Contract assets recorded on contracts during the period	0	8
Contract assets, ending	0	0
Contract liabilities
Contract liabilities, beginning	1,731	271
Recognition of revenue included in beginning of year contract liabilities	(1,679)	(199)
Contract liabilities, net of revenue recognized on contracts during the period	2,326	2,037
Contract liabilities, ending	$ 2,378	$ 2,109