Income Taxes (Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 347	$ 307	$ 291
Increases-prior period positions	28	127	34
Decreases-prior period positions	(106)	(119)	(75)
Increases-current period positions	43	64	61
Decreases-current period positions	0	(21)	0
Settlements with tax authorities	(4)	0	0
Expiration of statutes of limitation	(15)	(11)	(4)
Balance at December 31	293	347	307
Virginia Electric and Power Company
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	114	117	121
Increases-prior period positions	4	22	4
Decreases-prior period positions	(80)	(51)	(33)
Increases-current period positions	24	47	25
Decreases-current period positions	0	(21)	0
Settlements with tax authorities	(4)	0	0
Expiration of statutes of limitation	(1)	0	0
Balance at December 31	$ 57	$ 114	$ 117