SUPPLEMENTAL INFORMATION FOR STATEMENTS OF CASH FLOWS Schedule of Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Income taxes paid, net of refunds	$ 1,255	$ 283	$ 426
Interest paid to others, excluding capitalized interest	12,693	13,581	15,315
Proceeds from Interest Received	(3,374)	(1,099)	(760)
Schedule of non-cash investing and financing activities:
Settlement of accrued contingent liabilities through installment obligations	$ 0	$ 0	$ 386