Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	Dec. 31, 2022 USD ($) $ / MMBTU $ / MWh	Dec. 31, 2021 USD ($) $ / MMBTU $ / MWh
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 1,922	$ 1,391
Derivative Liabilities	(2,169)	(1,508)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	744	454
Derivative Liabilities	(1,018)	(594)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	963	643
Derivative Liabilities	$ (935)	$ (622)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.91)	(1.36)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	39.94	3.82
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	0.18	(0.04)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(29.41)	(11.70)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	15.00	6.65
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(3.04)	(2.01)
Recurring | Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 390	$ 218
Recurring | Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	135	66
Derivative Liabilities	(390)	(245)
Recurring | Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	243	143
Derivative Liabilities	$ (276)	$ (188)