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Fair Value Measurements (Fair Value, Option, Quantitative Disclosures) (Detail) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2022 USD ($) $ / MMBTU $ / MWh | Dec. 31, 2021 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | $ 2,469 | $ 613
Fair Value of Derivative Liabilities |  | 2,371 | 868
Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 961 | 300
Fair Value of Derivative Liabilities |  | 917 | 470
Fair Value, Measurements, Recurring |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Total assets |  | 7,772 | 8,161
Total liabilities |  | 2,371 | 868
Fair Value, Measurements, Recurring | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Total assets |  | 3,809 | 3,847
Total liabilities |  | 917 | 470
Fair Value, Measurements, Recurring | Commodity Contract |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 870 | 282
Fair Value of Derivative Liabilities |  | 1,509 | 469
Fair Value, Measurements, Recurring | Commodity Contract | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 359 | 146
Fair Value of Derivative Liabilities |  | 503 | 133
Fair Value, Measurements, Recurring | Level 3 |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Total assets |  | 499 | 230
Total liabilities |  | 17 | 8
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Total assets |  | 288 | 110
Total liabilities |  | 17 | 8
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 499 | 230
Fair Value of Derivative Liabilities |  | 17 | 8
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 288 | 110
Fair Value of Derivative Liabilities |  | $ 17 | $ 8
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract | Natural Gas | Minimum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [1] | (2) |
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract | Natural Gas | Maximum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [1] | 6 |
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract | Natural Gas | Weighted Average | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [1],[2] | (1) |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets | [1] | $ 1 |
Fair Value of Derivative Liabilities | [1] | 12 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets | [1] | 1 |
Fair Value of Derivative Liabilities | [1] | $ 12 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Minimum |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [1] | (2) |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Minimum | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | (2) |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Minimum | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | (2) |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Maximum |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [1] | 6 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Maximum | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 8 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Maximum | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 5 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Weighted Average |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [1],[2] | (1) |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Weighted Average | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [2],[3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Natural Gas | Weighted Average | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [2],[3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | $ 263 |
Fair Value of Derivative Liabilities |  | 5 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | 263 |
Fair Value of Derivative Liabilities |  | $ 5 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Minimum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Minimum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Minimum | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Minimum | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 1 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Maximum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 19 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Maximum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 19 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Maximum | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 10 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Maximum | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 10 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Weighted Average | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [2],[3] | 5 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Weighted Average | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [2],[3] | 5 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Weighted Average | Liabilities | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [2],[3] | 4 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | FTRs | Weighted Average | Liabilities | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [2],[3] | 4 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Electricity |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Assets |  | $ 211 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Electricity | Minimum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 28 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Electricity | Maximum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [3] | 199 |
Fair Value, Measurements, Recurring | Level 3 | Valuation, Income Approach | Commodity Contract | Electricity | Weighted Average | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MWh | [2],[3] | 51 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Liabilities | [1] | $ 24 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Fair Value of Derivative Liabilities | [1] | $ 24 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Minimum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 4 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Minimum | Assets | Price Volatility |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [4] | 13.00% |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Maximum | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 17 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Maximum | Assets | Price Volatility |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [4] | 70.00% |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Weighted Average | Assets | Market Price |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [2],[3] | 10 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity Contract | Natural Gas | Weighted Average | Assets | Price Volatility |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [2],[4] | 51.00% |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Minimum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 4 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Minimum | Assets | Price Volatility | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [4] | 8.00% |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Maximum | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [3] | 19 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Maximum | Assets | Price Volatility | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [4] | 31.00% |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Weighted Average | Assets | Market Price | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Market Price | $ / MMBTU | [2],[3] | 10 |
Fair Value, Measurements, Recurring | Level 3 | Option Model | Commodity | Natural Gas | Weighted Average | Assets | Price Volatility | Virginia Electric and Power Company |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |
Price volatility (percentage) | [2],[4] | 51.00% |
[1] | Includes basis.
[2] | Averages weighted by volume.
[3] | Represents market prices beyond defined terms for Levels 1 and 2.
[4] | Represents volatilities unrepresented in published markets.

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