v3.26.1
FAIR VALUE MEASUREMENTS AND DERIVATIVE INSTRUMENTS (Schedule of Financial Impact of Energy Contracts) (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]    
Percent of long-term trading contract gains shared with customers (percentage) 10.00%  
Operating Revenues $ 338,267 $ 365,736
Energy Derivative Contracts | Not Designated as Hedging Instrument    
Derivative Instruments, Gain (Loss) [Line Items]    
Unrealized Net Gain (Loss) (31,000) (3,000)
Operating Revenues $ 14,000 $ 21,000