Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Parenthetical) (Detail) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Derivatives Fair Value [Line Items]
Current derivative assets	[1]	$ 209	$ 67
Current derivative liabilities		729	412	[2]
Other Current Assets
Derivatives Fair Value [Line Items]
Current derivative assets		182	63
Current Liabilities Held for Sale
Derivatives Fair Value [Line Items]
Current derivative liabilities		$ 25	$ 3

[1] Current derivative assets include $182 million and $63 million in other current assets in Dominion Energy’s Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020, respectively.  The remainder is presented in current assets held for sale in Dominion Energy’s Consolidated Balance Sheets.

[2] Dominion Energy’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.