Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Detail) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021		Mar. 31, 2021	Dec. 31, 2020
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	[1]	$ 446	$ 283		$ 491	$ 179
Cash and cash equivalents		444	283	[2]
Restricted cash and equivalents	[3],[4]	148	125		71	68
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		594	408		562	247
Virginia Electric and Power Company
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		36	26	[5]	56	35
Restricted cash and equivalents	[4]	0	0		0	0
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		$ 36	$ 26		$ 56	$ 35

[1] At March 31, 2022, March 31, 2021 and December 31, 2020, Dominion Energy had $2 million, $14 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 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 March 31, 2021 and December 31, 2020, Dominion Energy had $3 million of restricted cash and equivalents included in current assets held for sale. No amounts were included in current assets held for sale at March 31, 2022 and December 31, 2021.

[4] Restricted cash and equivalent 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.