Significant Financing Transactions - (Commercial Paper, Bank Loans and Letters of Credit Outstanding) (Details) (USD $)	Jun. 30, 2012
Facility Limit	$ 3,500,000,000
Outstanding Commercial Paper	1,530,000,000
Outstanding Letters of Credit	36,000,000
Facility Capacity Available	1,934,000,000
Three Year Joint Revolving Credit Facility
Facility Limit	500,000,000	[1]
Outstanding Commercial Paper	0	[1]
Outstanding Letters of Credit	36,000,000	[1]
Facility Capacity Available	464,000,000	[1]
Credit Facility 1.5 Billion | Three Year Joint Revolving Credit Facility
Facility Limit	3,000,000,000	[2]
Outstanding Commercial Paper	1,530,000,000	[2]
Outstanding Letters of Credit	0	[2]
Facility Capacity Available	1,470,000,000	[2]
Credit Facility, to support letters of credit	1,500,000,000
Virginia Electric and Power Company
Facility Limit	1,250,000,000
Outstanding Commercial Paper	465,000,000
Outstanding Letters of Credit	15,000,000
Facility Capacity Available	770,000,000
Virginia Electric and Power Company | Three Year Joint Revolving Credit Facility
Facility Limit	250,000,000	[3]
Outstanding Commercial Paper	0	[3]
Outstanding Letters of Credit	15,000,000	[3]
Facility Capacity Available	235,000,000	[3]
Virginia Electric and Power Company | Credit Facility 1.5 Billion | Three Year Joint Revolving Credit Facility
Facility Limit	1,000,000,000	[2]
Outstanding Commercial Paper	465,000,000	[2]
Outstanding Letters of Credit	0	[2]
Facility Capacity Available	535,000,000	[2]
Credit Facility, to support letters of credit	$ 1,500,000,000

[1] This credit facility has a maturity date of September 2016, and can be used to support bank borrowings, commercial paper and letter of credit issuances.

[2] This credit facility has a maturity date of September 2016, and can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.5 billion of letters of credit.

[3] This credit facility has a maturity date of September 2016, and can be used to support bank borrowings, commercial paper and letter of credit issuances. Virginia Power's current sub-limit under this credit facility can be increased or decreased multiple times per year.