Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Detail) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	[1]	$ 283	$ 179	$ 166	$ 268
Cash and cash equivalents		283	172
Restricted cash and equivalents	[2],[3]	125	68	103	123
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		408	247	269	391
Virginia Electric and Power Company
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		26	35	17	29
Restricted cash and equivalents	[3]			7	9
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		$ 26	$ 35	$ 24	$ 38

[1] At December 31, 2020, December 31, 2019 and December 31, 2018, Dominion Energy had $7 million, $31 million and $110 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] At December 31, 2020, December 31, 2019 and December 31, 2018, Dominion Energy had $3 million, $12 million and $89 million of restricted cash included in current assets held for sale, respectively. No amounts were included in current assets held for sale at December 31, 2021.

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