Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Parenthetical) (Detail) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Current derivative assets	[1]	$ 67	$ 68
Noncurrent derivative assets	[2]	330	25
Other Current Assets
Derivatives Fair Value [Line Items]
Current derivative assets		63	61
Other Deferred Charges and Other Assets
Derivatives Fair Value [Line Items]
Noncurrent derivative assets		330	16
Other Current Liabilities
Derivatives Fair Value [Line Items]
Current derivative liabilities		412	394
Other Deferred Credits and Other Liabilities
Derivatives Fair Value [Line Items]
Noncurrent derivative liabilities		$ 71	$ 329

[1] Current derivative assets include $63 million and $61 million in other current assets in Dominion Energy’s Consolidated Balance Sheets as of December 31, 2020 and 2019, respectively. The remainder is recorded in current assets held for sale in Dominion Energy’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets include $330 million and $16 million in other deferred charges and other assets in Dominion Energy’s Consolidated Balance Sheets as of December 31, 2020 and 2019, respectively. The remainder is recorded in noncurrent assets held for sale in Dominion Energy’s Consolidated Balance Sheets.