Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Detail) - USD ($) $ in Millions		Sep. 30, 2024	Dec. 31, 2023		Sep. 30, 2023	Dec. 31, 2022
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	[1]	$ 1,776	$ 217		$ 176	$ 153
Cash and cash equivalents		1,776	184	[2]
Restricted cash and equivalents	[3],[4]	126	84		71	188
Restricted cash and equivalents			4		4	2
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		1,902	301		247	341
Virginia Electric and Power Company
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		28	90	[5]	37	22
Restricted cash and equivalents	[4],[6]	104				2
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		$ 132	$ 90		$ 37	$ 24

[1] At September 30, 2023, December 31, 2023 and December 31, 2022, Dominion Energy had $39 million, $33 million and $34 million, respectively, of cash and cash equivalents included in current assets held for sale.

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

[3] At September 30, 2023, December 31, 2023 and December 31, 2022, Dominion Energy had $4 million, $4 million and $2 million, respectively, of restricted cash and equivalents included in current assets held for sale with the remaining balances presented within other current assets in Dominion Energy’s Consolidated Balance Sheets.

[4] Includes $100 million attributable to VIEs at September 30, 2024.

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

[6] Restricted cash and equivalents balances are presented within other current assets in Virginia Power’s Consolidated Balance Sheets.