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, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Fair Value		$ 2,276
Cash equivalents and other, Amortized Cost	[1]	43	$ 84
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]	43	84
Amortized Cost, Total		3,811	3,699
Total Unrealized Gains		4,240	3,308
Total Unrealized Losses	[2]	(34)	(61)
Allowance for Credit Losses, Total		0	0
Fair Value, Total		8,017	6,946	[3]
Net assets related to pending sales of securities		21	49
Fair value of securities in an unrealized loss position		474	764
Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Fair Value		1,359
Cash equivalents and other, Amortized Cost	[1]	13	47
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]	13	47
Amortized Cost, Total		2,088	2,033
Total Unrealized Gains		2,201	1,726
Total Unrealized Losses	[2]	(23)	(43)
Allowance for Credit Losses, Total		0	0
Fair Value, Total		4,266	3,716	[4]
Net assets related to pending sales of securities		11	27
Fair value of securities in an unrealized loss position		262	384
Corporate Debt Fixed Income Securities
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	569	508
Fixed income securities Total Unrealized Gains	[5]	17	10
Fixed income securities Total Unrealized Losses	[5]	(17)	(27)
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	569	491
Corporate Debt Fixed Income Securities | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	357	292
Fixed income securities Total Unrealized Gains	[5]	8	3
Fixed income securities Total Unrealized Losses	[5]	(14)	(21)
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	351	274
Government Debt Fixed Income Securities
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	1,549	1,426
Fixed income securities Total Unrealized Gains	[5]	42	28
Fixed income securities Total Unrealized Losses	[5]	(15)	(24)
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	1,576	1,430
Government Debt Fixed Income Securities | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	894	811
Fixed income securities Total Unrealized Gains	[5]	25	17
Fixed income securities Total Unrealized Losses	[5]	(7)	(12)
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	912	816
Other
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	131
Fixed income securities Total Unrealized Gains	[5]	0
Fixed income securities Total Unrealized Losses	[5]	0
Fixed income securities Allowance for Credit Losses	[5]	0
Fixed income securities Fair Value	[5]	131
Other | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	96
Fixed income securities Total Unrealized Gains	[5]	0
Fixed income securities Total Unrealized Losses	[5]	0
Fixed income securities Allowance for Credit Losses	[5]	0
Fixed income securities Fair Value	[5]	96
Insurance Contracts
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	252	244
Fixed income securities Total Unrealized Gains	[5]	0	0
Fixed income securities Total Unrealized Losses	[5]	0	0
Fixed income securities Fair Value	[5]	252	244
U.S.
Debt Securities, Available-for-Sale [Line Items]
Equity securities Amortized Cost	[6]	1,267	1,276
Equity securities Total Unrealized Gains	[6]	4,181	3,270
Equity securities Total Unrealized Losses	[6]	(2)	(10)
Equity securities Fair Value	[6]	5,446	4,536
U.S. | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Equity securities Amortized Cost	[6]	728	759
Equity securities Total Unrealized Gains	[6]	2,168	1,706
Equity securities Total Unrealized Losses	[6]	(2)	(10)
Equity securities Fair Value	[6]	2,894	2,455
Common/collective trust funds | Fixed Income
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	0	161
Fixed income securities Total Unrealized Gains	[5]	0	0
Fixed income securities Total Unrealized Losses	[5]	0	0
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	0	161
Common/collective trust funds | Fixed Income | Virginia Electric and Power Company
Debt Securities, Available-for-Sale [Line Items]
Fixed income securities Amortized Cost, Total	[5]	0	124
Fixed income securities Total Unrealized Gains	[5]	0	0
Fixed income securities Total Unrealized Losses	[5]	0	0
Fixed income securities Allowance for Credit Losses	[5]	0	0
Fixed income securities Fair Value	[5]	$ 0	$ 124

[1] Dominion Energy includes pending sales of securities of $21 million and $49 million at September 30, 2024 and December 31, 2023, respectively. Virginia Power includes pending sales of securities of $11 million and $27 million at September 30, 2024, and December 31, 2023, respectively.

[2] Dominion Energy’s fair value of securities in an unrealized loss position was $474 million and $764 million at September 30, 2024 and December 31, 2023, respectively. Virginia Power’s fair value of securities in an unrealized loss position was $262 million and $384 million at September 30, 2024 and December 31, 2023, respectively.

[3] Dominion Energy’s Consolidated Balance Sheet at December 31, 2023 has been derived from the audited Consolidated Balance Sheet at that date.

[4] Virginia Power’s Consolidated Balance Sheet at December 31, 2023 has been derived from the audited Consolidated Balance Sheet at that date.

[5] 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).

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