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Investments (Equity and Fixed Income Securities, Insurance Contracts and Cash Equivalents in Decommissioning Trust Funds) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Fair Value |  | $ 2,082 |
Cash equivalents and other, Amortized Cost | [1] | 84 | $ 43
Cash equivalents and other, Total Unrealized Gains | [1] | 0 | 0
Cash equivalents and other, Total Unrealized Losses | [1] | 0 | 0
Cash equivalents and other, Allowance for Credit Losses | [1] | 0 | 0
Cash equivalents and other, Fair Value | [1] | 84 | 43
Amortized Cost, Total |  | 3,699 | 3,632
Total Unrealized Gains |  | 3,308 | 2,506
Total Unrealized Losses | [2] | (61) | (181)
Allowance for Credit Losses, Total |  | 0 | 0
Fair Value, Total |  | 6,946 | 5,957
Fair value of securities in an unrealized loss position |  | 764 | 1,600
Net assets related to pending sale of securities |  | 49 | 42
Virginia Electric and Power Company |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Fair Value |  | 1,214 |
Cash equivalents and other, Amortized Cost | [1] | 47 | 23
Cash equivalents and other, Total Unrealized Gains | [1] | 0 | 0
Cash equivalents and other, Total Unrealized Losses | [1] | 0 | 0
Cash equivalents and other, Fair Value | [1] | 47 | 23
Amortized Cost, Total |  | 2,033 | 2,012
Total Unrealized Gains |  | 1,726 | 1,307
Total Unrealized Losses | [2] | (43) | (117)
Allowance for Credit Losses, Total |  | 0 | 0
Fair Value, Total |  | 3,716 | 3,202
Fair value of securities in an unrealized loss position |  | 384 | 946
Net assets related to pending sale of securities |  | 27 | 24
Corporate Debt Fixed Income Securities |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 508 | 640
Fixed income securities Total Unrealized Gains | [3] | 10 | 1
Fixed income securities Total Unrealized Losses | [3] | (27) | (65)
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | 491 | 576
Corporate Debt Fixed Income Securities | Virginia Electric and Power Company |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 292 | 406
Fixed income securities Total Unrealized Gains | [3] | 3 | 1
Fixed income securities Total Unrealized Losses | [3] | (21) | (47)
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | 274 | 360
Government Debt Fixed Income Securities |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 1,426 | 1,252
Fixed income securities Total Unrealized Gains | [3] | 28 | 4
Fixed income securities Total Unrealized Losses | [3] | (24) | (70)
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | 1,430 | 1,186
Government Debt Fixed Income Securities | Virginia Electric and Power Company |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 811 | 664
Fixed income securities Total Unrealized Gains | [3] | 17 | 2
Fixed income securities Total Unrealized Losses | [3] | (12) | (35)
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | 816 | 631
Insurance Contracts |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total |  | 244 | 221
Fixed income securities Total Unrealized Gains |  | 0 | 0
Fixed income securities Total Unrealized Losses |  | 0 | 0
Fixed income securities Fair Value |  | 244 | 221
U.S. |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Equity securities Amortized Cost | [4] | 1,276 | 1,378
Equity securities Total Unrealized Gains | [4] | 3,270 | 2,501
Equity securities Total Unrealized Losses | [4] | (10) | (46)
Equity securities Fair Value | [4] | 4,536 | 3,833
U.S. | Virginia Electric and Power Company |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Equity securities Amortized Cost | [4] | 759 | 858
Equity securities Total Unrealized Gains | [4] | 1,706 | 1,304
Equity securities Total Unrealized Losses | [4] | (10) | (35)
Equity securities Fair Value | [4] | 2,455 | 2,127
Common/collective trust funds | Fixed Income |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 161 | 98
Fixed income securities Total Unrealized Gains | [3] | 0 | 0
Fixed income securities Total Unrealized Losses | [3] | 0 | 0
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | 161 | 98
Common/collective trust funds | Fixed Income | Virginia Electric and Power Company |  |  |
Debt Securities, Available-for-Sale [Line Items] |  |  |
Fixed income securities Amortized Cost, Total | [3] | 124 | 61
Fixed income securities Total Unrealized Gains | [3] | 0 | 0
Fixed income securities Total Unrealized Losses | [3] | 0 | 0
Fixed income securities Allowance for Credit Losses | [3] | 0 | 0
Fixed income securities Fair Value | [3] | $ 124 | $ 61
[1] | Dominion Energy includes pending sales of securities of $49 million and $42 million at December 31, 2023 and 2022, respectively. Virginia Power includes pending sales of securities of $27 million and $24 million at December 31, 2023 and 2022, respectively.
[2] | Dominion Energy’s fair value of securities in an unrealized loss position was $764 million and $1.6 billion at December 31, 2023 and 2022, respectively. Virginia Power’s fair value of securities in an unrealized loss position was $384 million and $946 million at December 31, 2023 and 2022, respectively.
[3] | Unrealized gains and losses on fixed income securities are included in AOCI and the nuclear decommissioning trust regulatory liability as discussed in Note 2. Changes in allowance for credit losses are included in other income
[4] | Unrealized gains and losses on equity securities are included in other income and the nuclear decommissioning trust regulatory liability as discussed in Note 2.

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