Derivatives - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) gal in Millions, certificate in Millions, T in Millions, MMBTU in Millions, $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2026 USD ($) certificate GWh MMBTU T gal	Dec. 31, 2025 USD ($) certificate GWh MMBTU T gal
Natural gas
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, energy measure \| MMBTU	3,799	3,742
Electricity
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, energy measure \| GWh	951,495	996,777
Financial transmission rights / Congestion revenue rights
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, energy measure \| GWh	284,597	249,400
Coal
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, mass \| T	23	22
Fuel oil
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, volume \| gal	24	8
Emissions
Derivatives, Fair Value [Line Items]
Derivative, nonmonetary notional amount, mass \| T	22	13
Renewable energy certificates
Derivatives, Fair Value [Line Items]
Nonmonetary notional volume \| certificate	27	31
Interest rate swaps – variable/fixed
Derivatives, Fair Value [Line Items]
Derivative, notional amount \| $	$ 414	$ 5,716
Interest rate swaps – fixed/variable
Derivatives, Fair Value [Line Items]
Derivative, notional amount \| $	$ 0	$ 700

Nominal number of units used to calculate payment on derivative.

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- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

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Nominal mass used to calculate payments on a derivative instrument.

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Nominal volume used to calculate payments on a derivative instrument.

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Nominal or face amount used to calculate payment on derivative.

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