Employee Benefit Plans (Fair Values of Pension and Post Retirement Plan Assets by Asset Category) (Detail) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[1]	$ 8,819	$ 8,670
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[2]	2,045	1,843
Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2,227	2,812
Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		961	876
Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2,643	2,534
Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		147	138
Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4,870	5,346
Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,108	1,014
NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	3,949	3,324
Cash equivalents and other | Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		21	14
Cash equivalents and other | Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		3	3
Cash equivalents and other | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		9	11
Cash equivalents and other | Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1	1
Cash equivalents and other | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		30	25
Cash equivalents and other | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	4
US Equity Securities | Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[4]	1,145	1,653
US Equity Securities | Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	757	685
US Equity Securities | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[4]		170
US Equity Securities | Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]		10
US Equity Securities | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[4]	1,145	1,823
US Equity Securities | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	757	695
Foreign Equity Securities | Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		944	1,034
Foreign Equity Securities | Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		194	181
Foreign Equity Securities | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2	5
Foreign Equity Securities | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		946	1,039
Foreign Equity Securities | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		194	181
Insurance Contracts | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		162	166
Insurance Contracts | Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		10	10
Insurance Contracts | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		162	166
Insurance Contracts | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		10	10
Corporate debt instruments | Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		74	65
Corporate debt instruments | Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	4
Corporate debt instruments | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		750	805
Corporate debt instruments | Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		36	38
Corporate debt instruments | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		824	870
Corporate debt instruments | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		40	42
Government securities | Level 1 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		43	46
Government securities | Level 1 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		3	3
Government securities | Level 2 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,720	1,377
Government securities | Level 2 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		100	79
Government securities | Fair Value, Inputs, Level 1, 2 and 3 | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,763	1,423
Government securities | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		103	82
Commingled funds/collective trust funds | NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	2,012	1,780
Commingled funds/collective trust funds | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	725	649
Real Estate Funds | NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	67	66
Real Estate Funds | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	11	11
Private Equity Funds | NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	1,395	1,284
Private Equity Funds | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	173	158
Fixed Income Funds | NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	236	192
Fixed Income Funds | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	14	11
Hedge Funds | NAV | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[3]	239	2
Hedge Funds | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	14	0
Investments Measured At Fair Value Including Excluding Pending Purchases Sales And Accrued Income | NAV | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[6]	$ 937	$ 829

[1] Excludes net assets related to pending sales of securities of $298 million, net accrued income of $24 million, and includes net assets related to pending purchases of securities of $54 million at December 31, 2023. Excludes net assets related to pending sales of securities and advanced subscription of $177 million, net accrued income of $27 million, and includes net assets related to pending purchases of securities of $180 million at December 31, 2022.

[2] Excludes net assets related to pending sales of securities and advanced subscription of $17 million, net accrued income of $2 million, and includes net assets related to pending purchases of securities of $2 million at December 31, 2023. Excludes net assets related to pending sales of securities and advanced subscription of $10 million, net accrued income of $2 million, and includes net assets related to pending purchases of securities of $10 million at December 31, 2022.

[3] These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.

[4] No amounts of Dominion Energy preferred stock were held at December 31, 2023. Includes $170 million of Dominion Energy preferred stock at December 31, 2022.

[5] No amounts of Dominion Energy preferred stock were held at December 31, 2023. Includes $10 million of Dominion Energy preferred stock at December 31, 2022.

[6] These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.