Fair Value of Financial Instruments - Significant Unobservable Inputs Used in Fair Value of Level 3 Positions (Details) $ in Millions	Dec. 31, 2022 USD ($) $ / MWh	Dec. 31, 2021 USD ($) $ / MWh
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Cash collateral paid in support of energy risk management activities	$ 260	$ 291
Cash collateral received in support of energy risk management activities	1,708	845
Commodity contracts
Assets
Derivative Assets	11,976	7,139
Liabilities
Derivative Liabilities	8,439	4,798
Commodity contracts | Level 3
Assets
Derivative Assets	1,251	457
Liabilities
Derivative Liabilities	746	164
Commodity contracts | Natural Gas Contracts | Level 3
Assets
Derivative Assets		16
Liabilities
Derivative Liabilities		$ 1
Commodity contracts | Natural Gas Contracts | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh		3
Commodity contracts | Natural Gas Contracts | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh		40
Commodity contracts | Natural Gas Contracts | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh		15
Commodity contracts | Fair Value, Measurements, Recurring | Level 3
Assets
Derivative Assets	1,251	$ 457
Liabilities
Derivative Liabilities	746	164
Commodity contracts | Fair Value, Measurements, Recurring | Natural Gas Contracts | Level 3
Assets
Derivative Assets	340
Liabilities
Derivative Liabilities	$ 448
Commodity contracts | Fair Value, Measurements, Recurring | Natural Gas Contracts | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	2
Commodity contracts | Fair Value, Measurements, Recurring | Natural Gas Contracts | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	48
Commodity contracts | Fair Value, Measurements, Recurring | Natural Gas Contracts | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	6
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3
Assets
Derivative Assets	$ 843	392
Liabilities
Derivative Liabilities	$ 216	$ 121
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	3	3
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	431	212
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	48	35
Commodity contracts | Fair Value, Measurements, Recurring | FTRs | Level 3
Assets
Derivative Assets	$ 68	$ 49
Liabilities
Derivative Liabilities	$ 82	$ 42
Commodity contracts | Fair Value, Measurements, Recurring | FTRs | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	(32)	(122)
Commodity contracts | Fair Value, Measurements, Recurring | FTRs | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	610	43
Commodity contracts | Fair Value, Measurements, Recurring | FTRs | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	0	0