FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value of Financial Assets and Liabilities
Risk premium percentage	1.83%
Level 1
Fair Value of Financial Assets and Liabilities
Long-term debt, including current maturities, net	$ 0	$ 0
Level 2
Fair Value of Financial Assets and Liabilities
Long-term debt, including current maturities, net	944,447	873,454
Level 3
Fair Value of Financial Assets and Liabilities
Long-term debt, including current maturities, net	0	0
Total
Fair Value of Financial Assets and Liabilities
Long-term debt, including current maturities, net	944,447	873,454
Cost
Fair Value of Financial Assets and Liabilities
Long-term debt, including current maturities, net	$ 786,227	$ 808,622