COMMITMENTS AND CONTINGENCIES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating leases
Other assets: Other	$ 15,318	$ 15,589
Other accrued liabilities	1,802	1,757
Other long-term liabilities	13,601	13,868
Total	15,403	15,625
Finance leases
Depreciable plant and equipment	19,494	18,207
Accumulated depreciation and amortization	12,411	10,813
Net utility plant	7,083	7,394
Current maturities of long-term debt, net	809	721
Long-term debt, net	4,918	4,483
Total finance lease liabilities	$ 5,727	$ 5,204
Weighted average remaining lease term
Operating leases	129 months	135 months
Finance leases	46 months	64 months
Weighted average discount rate
Operating leases	3.40%	3.50%
Finance leases	4.60%	5.50%
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other accrued liabilities	Other accrued liabilities