Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	Dec. 31, 2025 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2024 USD ($) $ / MMBTU $ / MWh
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 707	$ 694
Derivative Liabilities	(597)	(605)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	372	428
Derivative Liabilities	(329)	(410)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	275	187
Derivative Liabilities	(235)	(150)
Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	153	166
Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	109	105
Derivative Liabilities	(82)	(123)
Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	33	51
Derivative Liabilities	$ (52)	$ (27)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.35)	(1.24)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	9.33	9.96
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.13)	(0.05)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(21.82)	(16.34)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	17.79	17.28
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(5.58)	(2.74)