DERIVATIVES - Schedule of Gain (Loss) On Natural Gas Purchase Derivatives (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Non-cash (gain) loss from natural gas purchase derivatives	$ (20)	$ (4)	$ (8)	$ (22)
Settlements	25	7	37	19
Net loss (gain) from natural gas purchase derivatives	$ 5	$ 3	$ 29	$ (3)

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

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