v3.24.0.1
REGULATORY MATTERS (Regulatory Liabilities) (Details) - USD ($)
$ in Thousands
Dec. 31, 2023
Dec. 31, 2022
Regulatory Liabilities [Line Items]    
Regulatory Liabilities, Remaining Recovery Period (years) 1 year  
Total Regulatory Liabilities $ 489,000 $ 489,000
Less Current Portion 92,740 110,782
Total Non-Current Regulatory Liabilities 396,061 377,546
Income Taxes Payable through Future Rates    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities 229,000 244,000
Net Cost of Removal    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities 130,000 43,000
Renewable Energy Standard    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities $ 77,000 73,000
Derivatives    
Regulatory Liabilities [Line Items]    
Regulatory Liabilities, Remaining Recovery Period (years) 6 years  
Total Regulatory Liabilities $ 28,000 86,000
Demand Side Management    
Regulatory Liabilities [Line Items]    
Regulatory Liabilities, Remaining Recovery Period (years) 1 year  
Total Regulatory Liabilities $ 9,000 16,000
Deferred Investment Tax Credits    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities $ 6,000 7,000
Transmission Balancing Accounts    
Regulatory Liabilities [Line Items]    
Regulatory Liabilities, Remaining Recovery Period (years) 1 year  
Total Regulatory Liabilities $ 5,000 9,000
Pension and Other Postretirement Benefits    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities $ 4,000 8,000
Transmission Revenue Subject to Refund - FERC    
Regulatory Liabilities [Line Items]    
Regulatory Liabilities, Remaining Recovery Period (years) 1 year  
Total Regulatory Liabilities $ 0 1,000
Other Regulatory Liabilities    
Regulatory Liabilities [Line Items]    
Total Regulatory Liabilities $ 1,000 $ 2,000