Related-Party Transactions (Narrative) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Derivative assets	$ 2,469,000,000		$ 2,469,000,000		$ 613,000,000
Derivative liabilities	2,371,000,000		2,371,000,000		868,000,000
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Derivative assets	961,000,000		961,000,000		300,000,000
Derivative liabilities	917,000,000		917,000,000		470,000,000
Payable to affiliates	784,000,000		784,000,000		699,000,000	[1]
Outstanding borrowings, net of repayments, under money pool for non-regulated subsidiaries	$ 0		$ 0		0
Issuance of common stock to Dominion	0	0	0	0
Virginia Electric and Power Company | Pension Benefits | Amounts Associated With Dominion Pension Plan
Related Party Transaction [Line Items]
Amounts due to Dominion, noncurrent	$ 576,000,000		$ 576,000,000		522,000,000
Payment to be paid to Dominion, in 2022	175,000,000		175,000,000
Virginia Electric and Power Company | Medical Coverage for Local retirees | Amounts Associated with the Dominion Retiree Health and Welfare Plan
Related Party Transaction [Line Items]
Amounts due from Dominion, noncurrent	493,000,000		493,000,000		431,000,000
Virginia Electric and Power Company | Affiliated Entity
Related Party Transaction [Line Items]
Derivative assets	64,000,000		64,000,000		29,000,000
Derivative liabilities	3,000,000		3,000,000		6,000,000
Virginia Electric and Power Company | Principal Owner | Short-Term Borrowing Arrangements
Related Party Transaction [Line Items]
Payable to affiliates	$ 784,000,000		$ 784,000,000		$ 699,000,000

[1] Virginia Power’s Consolidated Balance Sheet at December 31, 2021 has been derived from the audited Consolidated Balance Sheet at that date.