v3.24.0.1
FAIR VALUE MEASUREMENTS AND DERIVATIVE INSTRUMENTS (Financial Impact of Derivative Energy Contracts) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]      
Unrealized Net Gain (Loss) $ (3,615) $ (55,522) $ (17,190)
Percent of long-term trading contract gains shared with customers (percentage) 10.00%    
Operating Revenues $ 1,875,448 1,808,082 1,592,586
Energy Derivative Contracts | Not Designated as Hedging Instrument      
Derivative Instruments, Gain (Loss) [Line Items]      
Unrealized Net Gain (Loss) (81,000) 72,000 62,000
Operating Revenues $ 18,000 $ 11,000 $ 7,000