FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Liabilities:
Convertible Notes, Carrying Value	$ 105,791	$ 105,974
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Deferred compensation assets	1,647	1,743
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Deferred compensation assets	389	484
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Deferred compensation assets	1,258	1,259
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Deferred compensation assets	0	$ 0
Convertible Debt [Member]
Liabilities:
Convertible Notes, Fair Value Disclosure	$ 100,900