COMMITMENTS AND CONTINGENCIES - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 2,464	$ 2,284
Finance lease cost:
Amortization of right-of-use assets	1,598	1,169
Interest on lease liabilities	282	306
Total finance lease cost	1,880	1,475
Short-term lease cost	2,079	2,048
Variable lease cost	415	306
Total lease cost	6,838	6,113
Depreciable plant and equipment	19,494	18,207
Finance Lease, Right-of-Use Asset, Accumulated Amortization	(12,411)	(10,813)
Net utility plant	$ 7,083	$ 7,394
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Current maturities of long-term debt, net	Current maturities of long-term debt, net
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-term debt, net	Long-term debt, net
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other	Other
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other accrued liabilities	Other accrued liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other long-term liabilities	Other long-term liabilities