INVESTMENTS (Details) - Investments Classified by Contractual Maturity Date $ in Thousands	Mar. 31, 2021 USD ($)
Investments Classified by Contractual Maturity Date [Abstract]
Net Carrying Amount, Convertible debentures	$ 8,957	[1]
Net Carrying Amount , Due after five years through ten years	1,000
Net Carrying Amount, Total	9,957
Fair Value, Convertible debentures	23,927	[1]
Fair Value, Due after five years through ten years	1,000
Fair Value, Total	$ 24,927

[1] Principal payments are due quarterly.