Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	Dec. 31, 2024 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2023 USD ($) $ / MMBTU $ / MWh
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 694	$ 1,197
Derivative Liabilities	(605)	(1,172)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	428	637
Derivative Liabilities	(410)	(615)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	187	421
Derivative Liabilities	$ (150)	$ (388)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.24)	(1.57)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	9.96	6.27
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.05)	(0.08)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(16.34)	(18.49)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	17.28	15.47
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(2.74)	(3.99)
Recurring | Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 166	$ 350
Recurring | Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	105	179
Derivative Liabilities	(123)	(157)
Recurring | Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	51	163
Derivative Liabilities	$ (27)	$ (116)