Investments (Equity and Fixed Income Securities, Insurance Contracts and Cash Equivalents in Decommissioning Trust Funds) (Detail) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Fair Value		$ 1,807
Amortized Cost, Total		3,660	$ 3,632
Total Unrealized Gains		2,860	2,506
Total Unrealized Losses	[1]	(175)	(181)
Allowance for Credit Losses, Total		0	0
Fair Value, Total		6,345	5,957	[2]
Net assets related to pending sales of securities		39	42
Fair value of securities in an unrealized loss position		1,900	1,600
Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Fair Value		1,025
Amortized Cost, Total		2,026	2,012
Total Unrealized Gains		1,490	1,307
Total Unrealized Losses	[1]	(116)	(117)
Allowance for Credit Losses, Total		0	0
Fair Value, Total		3,400	3,202	[3]
Net assets related to pending sales of securities		20	24
Fair value of securities in an unrealized loss position		1,100	946
Corporate Debt Fixed Income Securities
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[4]	545	640
Fixed income securities Total Unrealized Gains	[4]	0	1
Fixed income securities Total Unrealized Losses	[4]	(53)	(65)
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	492	576
Corporate Debt Fixed Income Securities | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[4]	324	406
Fixed income securities Total Unrealized Gains	[4]	0	1
Fixed income securities Total Unrealized Losses	[4]	(39)	(47)
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	285	360
Government Debt Fixed Income Securities
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[4]	1,340	1,252
Fixed income securities Total Unrealized Gains	[4]	0	4
Fixed income securities Total Unrealized Losses	[4]	(91)	(70)
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	1,249	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	[4]	737	664
Fixed income securities Total Unrealized Gains	[4]	0	2
Fixed income securities Total Unrealized Losses	[4]	(49)	(35)
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	688	631
Insurance Contracts
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total		228	221
Fixed income securities Total Unrealized Gains		0	0
Fixed income securities Total Unrealized Losses		0	0	[4]
Fixed income securities Fair Value		228	221
U.S.
Debt Securities, Available-for-Sale [Line Items]
Equity securities Amortized Cost	[5]	1,399	1,378
Equity securities Total Unrealized Gains	[5]	2,860	2,501
Equity securities Total Unrealized Losses	[5]	(31)	(46)
Equity securities Fair Value	[5]	4,228	3,833
U.S. | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Equity securities Amortized Cost	[5]	870	858
Equity securities Total Unrealized Gains	[5]	1,490	1,304
Equity securities Total Unrealized Losses	[5]	(28)	(35)
Equity securities Fair Value	[5]	2,332	2,127
Common/collective trust funds | Fixed Income
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[4]	66	98
Fixed income securities Total Unrealized Gains	[4]	0	0
Fixed income securities Total Unrealized Losses	[4]	0	0
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	66	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	[4]	52	61
Fixed income securities Total Unrealized Gains	[4]	0	0
Fixed income securities Total Unrealized Losses	[4]	0	0
Fixed income securities Allowance for Credit Losses	[4]	0	0
Fixed income securities Fair Value	[4]	52	61
Cash equivalents and other
Debt Securities, Available-for-Sale [Line Items]
Cash equivalents and other, Amortized Cost	[6]	82	43
Cash equivalents and other, Total Unrealized Gains	[6]	0	0
Cash equivalents and other, Total Unrealized Losses	[6]	0	0
Cash equivalents and other, Allowance for Credit Losses	[6]	0	0
Cash equivalents and other, Fair Value	[6]	82	43
Cash equivalents and other | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Cash equivalents and other, Amortized Cost	[6]	43	23
Cash equivalents and other, Total Unrealized Gains	[6]	0	0
Cash equivalents and other, Total Unrealized Losses	[6]	0	0
Cash equivalents and other, Allowance for Credit Losses	[6]	0	0
Cash equivalents and other, Fair Value	[6]	$ 43	$ 23

[1] Dominion Energy's fair value of securities in an unrealized loss position was $1.9 billion and $1.6 billion at September 30, 2023 and December 31, 2022, respectively. Virginia Power's fair value of securities in an unrealized loss position was $1.1 billion and $946 million at September 30, 2023 and December 31, 2022, respectively.

[2] Dominion Energy’s Consolidated Balance Sheet at December 31, 2022 has been derived from the audited Consolidated Balance Sheet at that date and recast for certain events as discussed in Note 1.

[3] Virginia Power’s Consolidated Balance Sheet at December 31, 2022 has been derived from the audited Consolidated Balance Sheet at that date.

[4] Unrealized gains and losses on fixed income securities are included in AOCI and the nuclear decommissioning trust regulatory liability. Changes in allowance for credit losses are included in other income (expense).

[5] Unrealized gains and losses on equity securities are included in other income (expense) and the nuclear decommissioning trust regulatory liability.

[6] Dominion Energy includes pending sales of securities of $39 million and $42 million at September 30, 2023 and December 31, 2022, respectively. Virginia Power includes pending sales of securities of $20 million and $24 million at September 30, 2023, and December 31, 2022, respectively.