Variable Interest Entities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Payment for electric capacity	$ 116,000,000	$ 109,000,000	$ 235,000,000	$ 217,000,000
Maximum [Member]
Contracts expiry date			2021
Minimum [Member]
Contracts expiry date			2015
Virginia Power [Member]
Aggregate generation capacity from long-term power and capacity contracts (MW)			870
Remaining purchase commitments			1,400,000,000
Payment for electric capacity	52,000,000	53,000,000	105,000,000	107,000,000
Payment for electric energy	$ 26,000,000	$ 34,000,000	$ 65,000,000	$ 75,000,000