Investments (Recorded Other-Than-Temporary Impairment Losses on Investments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Total other-than-temporary impairment losses	$ 26	[1]	$ 75	[1]	$ 59	[1]
Losses recorded to decommissioning trust regulatory liability	(10)		(24)		(21)
Losses recognized in other comprehensive income (before taxes)	2		3		3
Net impairment losses recognized in earnings	14		48		35
Other-than-temporary impairment losses for debt securities	4		6		10
Virginia Electric and Power Company
Schedule of Available-for-sale Securities [Line Items]
Total other-than-temporary impairment losses	11	[2]	29	[2]	25	[2]
Losses recorded to decommissioning trust regulatory liability	(10)		(24)		(21)
Losses recognized in other comprehensive income (before taxes)	0		1		1
Net impairment losses recognized in earnings	1		4		3
Other-than-temporary impairment losses for debt securities	$ 2		$ 4		$ 6

[1] Amounts include other-than-temporary impairment losses for debt securities of $4 million, $6 million and $10 million at December 31, 2012, 2011 and 2010, respectively.

[2] Amounts include other-than-temporary impairment losses for debt securities of $2 million, $4 million and $6 million at December 31, 2012, 2011 and 2010, respectively.