Risk Management, Derivative Instruments and Hedging Activities - Statements of Operations Presentation (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on commodity contracts	$ 92	$ 91	$ (90)	$ (44)
Realized and unrealized gain (loss) on interest rate contracts	218	100	(50)	157
Interest rate derivatives
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized and unrealized gain (loss) on interest rate contracts	0	1	(13)	9
Energy Revenues
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on commodity contracts	43	38	16	196
Fuel and Energy Purchases
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on commodity contracts	(5)	(8)	19	(7)
Operating Revenues
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on commodity contracts	176	76	(65)	(32)
Energy Expenses
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on commodity contracts	$ (84)	$ 15	$ (25)	$ (12)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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The difference between the book value and the sale price of agreements to purchase or sell mineral resources, energy, and agricultural products at some future point. This element refers to the gain (loss) included in earnings and not to the cash proceeds.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open agreements to purchase or sell mineral resources, energy, and agricultural products at some future point held at each balance sheet date, that was included in earnings for the period.

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