Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Detail) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021		Sep. 30, 2021	Dec. 31, 2020
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	[1]	$ 163	$ 283		$ 195	$ 179
Cash and cash equivalents		163	283	[2]
Restricted cash and equivalents	[3],[4]	177	125		72	68
Restricted cash and equivalents		0	0		22	3
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		340	408		267	247
Virginia Electric and Power Company
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		18	26	[5]	38	35
Restricted cash and equivalents	[4]	2	0		1	0
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		$ 20	$ 26		$ 39	$ 35

[1] At September 30, 2021 and December 31, 2020, Dominion Energy had $15 million and $7 million of cash and cash equivalents included in current assets held for sale, respectively. No amounts were included in current assets held for sale at September 30, 2022 and December 31, 2021.

[2] Dominion Energy’s Consolidated Balance Sheet at December 31, 2021 has been derived from the audited Consolidated Balance Sheet at that date.

[3] At September 30, 2021 and December 31, 2020, Dominion Energy had $22 million and $3 million of restricted cash and equivalents included in current assets held for sale, respectively. No amounts were included in current assets held for sale at September 30, 2022 and December 31, 2021.

[4] Restricted cash and equivalents balances are presented within other current assets in the Companies’ Consolidated Balance Sheets.

[5] Virginia Power’s Consolidated Balance Sheet at December 31, 2021 has been derived from the audited Consolidated Balance Sheet at that date.