Equity (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended
	May 05, 2022	Aug. 31, 2021	Jul. 31, 2021	Sep. 30, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock, par value				$ 0	$ 0
Common stock, shares authorized				50,000,000	50,000,000
Common stock, shares issued				40,300,000	40,300,000
Common stock, shares outstanding				40,300,000	40,300,000
Preferred stock, par value				$ 0	$ 0
Preferred stock, shares authorized				20,000,000	20,000,000
Preferred stock, shares issued				1,000	1,000
Preferred stock, shares outstanding				1,000	1,000
Dominion Energy | SCDOR [Member] | Common Stock
Class Of Stock [Line Items]
Common stock issued to satisfy the settlement	$ 72	$ 45
Dominion Energy | FILOT [Member] | Common Stock
Class Of Stock [Line Items]
Common stock issued to satisfy the settlement			$ 104