REVENUE RECOGNITION - Schedule of Changes in Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Contract assets
Contract assets, beginning	$ 0	$ 36
Contract assets at beginning of year transferred to accounts receivable	0	(36)
Contract assets recorded on contracts during the period	0	8
Contract assets, ending	0	8
Contract liabilities
Contract liabilities, beginning	1,731	271
Recognition of revenue included in beginning of year contract liabilities	(1,082)	(147)
Contract liabilities, net of revenue recognized on contracts during the period	427	63
Contract liabilities, ending	$ 1,076	$ 187