REVENUE RECOGNITION - Schedule of Changes in Contract Asset and Liability Balances (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Contract assets
Contract assets, beginning	$ 36,000	$ 67,000
Contract assets at beginning of year transferred to accounts receivable	0	(42,000)
Contract assets recorded on contracts during the period	13,000	2,000
Contract assets, ending	49,000	27,000
Contract liabilities
Contract liabilities, beginning	271,000	140,000
Recognition of revenue included in beginning of year contract liabilities	(112,000)	(72,000)
Contract liabilities, net of revenue recognized on contracts during the period	45,000	208,000
Foreign currently translation	0	2,000
Contract liabilities, ending	$ 204,000	$ 278,000