Fair Value of Financial Instruments - Significant Unobservable Inputs Used in Fair Value of Level 3 Positions (Details) $ in Millions	Dec. 31, 2025 USD ($) certificate $ / MWh $ / MMBTU $ / MWd	Dec. 31, 2024 USD ($) $ / MWh certificate $ / MWd
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Cash collateral paid in support of energy risk management activities	$ 365	$ 309
Cash collateral received in support of energy risk management activities	260	199
Commodity contracts
Assets
Derivative Assets	3,754	4,365
Liabilities
Derivative Liabilities	3,070	3,197
Commodity contracts | Level 3
Assets
Derivative Assets	313	195
Liabilities
Derivative Liabilities	486	359
Consumer Financing Program
Assets
Derivative Assets	0	9
Liabilities
Derivative Liabilities	4	3
Consumer Financing Program | Level 3
Assets
Derivative Assets	0	$ 0
Liabilities
Derivative Liabilities	0
Consumer Financing Program | Level 3 | Low | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.0200
Consumer Financing Program | Level 3 | Low | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.0600
Consumer Financing Program | Level 3 | High | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.0300
Consumer Financing Program | Level 3 | High | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.6000
Consumer Financing Program | Level 3 | Weighted Average | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.0283
Consumer Financing Program | Level 3 | Weighted Average | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability		0.1422
Natural Gas Contracts | Commodity contracts | Level 3
Assets
Derivative Assets	47	$ 56
Liabilities
Derivative Liabilities	$ 40	$ 15
Natural Gas Contracts | Commodity contracts | Level 3 | Low | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh		2
Natural Gas Contracts | Commodity contracts | Level 3 | Low | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MMBTU	0
Natural Gas Contracts | Commodity contracts | Level 3 | High | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh		27
Natural Gas Contracts | Commodity contracts | Level 3 | High | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MMBTU	17
Natural Gas Contracts | Commodity contracts | Level 3 | Weighted Average | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh		4,000,000
Natural Gas Contracts | Commodity contracts | Level 3 | Weighted Average | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MMBTU	5,000,000
Power Contracts | Commodity contracts | Level 3
Assets
Derivative Assets	$ 168	$ 57
Liabilities
Derivative Liabilities	$ 64	$ 86
Power Contracts | Commodity contracts | Level 3 | Low | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh	0	0
Power Contracts | Commodity contracts | Level 3 | High | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh	125	109
Power Contracts | Commodity contracts | Level 3 | Weighted Average | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWh	29,000,000	39,000,000
Capacity Contracts | Capacity Contracts | Level 3
Assets
Derivative Assets	$ 20	$ 34
Liabilities
Derivative Liabilities	$ 18	$ 13
Capacity Contracts | Capacity Contracts | Level 3 | Low | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWd	49	16
Capacity Contracts | Capacity Contracts | Level 3 | High | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWd	577	510
Capacity Contracts | Capacity Contracts | Level 3 | Weighted Average | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | $ / MWd	270,000,000	220,000,000
Renewables Energy Certificates | Level 3
Assets
Derivative Assets	$ 12	$ 30
Liabilities
Derivative Liabilities	$ 25	$ 14
Renewables Energy Certificates | Level 3 | Low | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | certificate	2	2
Renewables Energy Certificates | Level 3 | High | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | certificate	370	375
Renewables Energy Certificates | Level 3 | Weighted Average | Forward Market Price (perMMBtu) or (per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input | certificate	17,000,000	15,000,000
FTRs | Commodity contracts | Level 3
Assets
Derivative Assets	$ 22	$ 18
Liabilities
Derivative Liabilities	$ 11	$ 28
FTRs | Commodity contracts | Level 3 | Low | Auction Prices ($ per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	(50)	(50)
FTRs | Commodity contracts | Level 3 | High | Auction Prices ($ per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	19,100	16,180
FTRs | Commodity contracts | Level 3 | Weighted Average | Auction Prices ($ per MWh) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	0	0
Power Options | Level 3 | Low | Volatilities | Valuation Technique Option Model
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	0.22
Power Options | Level 3 | High | Volatilities | Valuation Technique Option Model
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	5.17
Power Options | Level 3 | Weighted Average | Volatilities | Valuation Technique Option Model
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative asset/ liability measurement input	1.10
Power Options | Power Options | Level 3
Assets
Derivative Assets	$ 44
Liabilities
Derivative Liabilities	45
Consumer Financing Program | Consumer Financing Program | Level 3
Assets
Derivative Assets	0	$ 0
Liabilities
Derivative Liabilities	$ 283	$ 203
Consumer Financing Program | Consumer Financing Program | Level 3 | Low | Collateral Default Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0118	0.0052
Consumer Financing Program | Consumer Financing Program | Level 3 | Low | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0200
Consumer Financing Program | Consumer Financing Program | Level 3 | Low | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0640
Consumer Financing Program | Consumer Financing Program | Level 3 | High | Collateral Default Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.4200	0.7680
Consumer Financing Program | Consumer Financing Program | Level 3 | High | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0300
Consumer Financing Program | Consumer Financing Program | Level 3 | High | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.6000
Consumer Financing Program | Consumer Financing Program | Level 3 | Weighted Average | Collateral Default Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0786	0.1171
Consumer Financing Program | Consumer Financing Program | Level 3 | Weighted Average | Collateral Prepayment Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.0252
Consumer Financing Program | Consumer Financing Program | Level 3 | Weighted Average | Credit Loss Rates | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Derivative liability	0.1694