FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Notes Payable	$ 105,974	$ 101,587
Financial Liabilities:
Convertible Debt, Fair Value Disclosures	104,900
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Deferred compensation assets	1,743	2,035
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Deferred compensation assets	484	493
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Deferred compensation assets	1,259	1,542
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Deferred compensation assets	0	0
Acquired Individual Deferred Compensation Arrangement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Plan Assets	$ 1,300	$ 1,500