Significant Financing Transactions (Commercial Paper, Bank Loans and Letters of Credit Outstanding) (Detail)	Mar. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Facility Limit	$ 6,000,000,000	[1]
Outstanding Commercial Paper	2,477,000,000	[1]
Outstanding Letters of Credit	99,000,000	[1]
Facility Capacity Available	3,424,000,000	[1]
Virginia Electric and Power Company
Line of Credit Facility [Line Items]
Facility Limit	6,000,000,000	[2]
Outstanding Commercial Paper	420,000,000	[2]
Outstanding Letters of Credit	$ 12,000,000	[2]

[1] This credit facility matures in March 2023 and can be used by the borrowers under the credit facility to support bank borrowings and the issuance of commercial paper, as well as to support up to a combined $2.0 billion of letters of credit.

[2] The full amount of the facility is available to Virginia Power, less any amounts outstanding to co-borrowers Dominion Energy, Questar Gas and DESC. The sub-limit for Virginia Power is set within the facility limit but can be changed at the option of the borrowers under the credit facility multiple times per year. At March 31, 2021, the sub-limit for Virginia Power was $1.5 billion. If Virginia Power has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in March 2023 and can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $2.0 billion (or the sub-limit, whichever is less) of letters of credit.