COMMITMENTS AND CONTINGENCIES - Supplemental Balance Sheet Information (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Operating leases
Other assets: Other	$ 14,402
Other accrued liabilities	1,452
Other long-term liabilities	12,928
Total	14,380
Finance leases
Depreciable plant and equipment	18,207
Accumulated depreciation and amortization	(9,644)
Net utility plant	8,563
Current maturities of long-term debt, net	680
Long-term debt, net	5,205
Total finance lease liabilities	$ 5,885
Weighted average remaining lease term
Operating leases	152 months
Finance leases	76 months
Weighted average discount rate
Operating leases	3.70%
Finance leases	5.50%