DERIVATIVES - Schedule of Gain (Loss) On Natural Gas Purchase Derivatives (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Non-cash (gain) loss from natural gas purchase derivatives	$ (14)	$ 24	$ (22)	$ 2
Settlements	13	3	50	22
Net (gain) loss from natural gas purchase derivatives	$ (1)	$ 27	$ 28	$ 24

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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