Significant Financing Transactions (Commercial Paper, Bank Loans and Letters of Credit Outstanding) (Parenthetical) (Detail) - USD ($)		Mar. 31, 2025	Mar. 31, 2023
Line of Credit Facility [Line Items]
Facility Limit	[1]	$ 6,000,000,000
Virginia Electric and Power Company
Line of Credit Facility [Line Items]
Facility Limit		6,000,000,000
Letter of Credit Matures in April 2032
Line of Credit Facility [Line Items]
Facility Limit		3,000,000,000
Line of Credit Sub-Limit | Virginia Electric and Power Company
Line of Credit Facility [Line Items]
Facility Limit		1,750,000,000
Letter of Credit
Line of Credit Facility [Line Items]
Facility Limit			$ 100,000,000
Letter of Credit | Virginia Electric and Power Company
Line of Credit Facility [Line Items]
Facility Limit		$ 3,000,000,000	$ 300,000,000

[1] This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032, 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 $3.0 billion of letters of credit