FINANCING RECEIVABLES - Financing Receivables and Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Financed receivables include installment receivable amounts which are due subsequent to one year
Gross financing receivables, short-term	$ 18,798	$ 17,695
Gross financing receivables, long-term	21,771	18,178
Allowance for doubtful accounts	(2,892)	(3,157)
Net financing receivables	37,677	32,716
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	3,157	3,288
Additions to allowance	1,424	890
Deductions, net of recoveries	(1,689)	(1,021)
Balance, end of period	$ 2,892	$ 3,157