REVENUE (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) customer	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) customer
Concentration Risk [Line Items]
Contract liability balances related to extended service contracts	$ 700		$ 700		$ 331
Recognized revenue related to contract liability balances	0	$ 0	0	$ 0
Contract assets	$ 0		$ 0		$ 0
Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Number of customer | customer			1		1
Concentration Risk, Benchmark Description			one customer with a trade account receivable balance greater than 10% of total accounts receivable, which account subsequently decreased to less than 10%		one customer with a trade account receivable balance greater than 10% of total accounts receivable, which account subsequently decreased to less than 10%