Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Virginia Electric and Power Company	Dec. 31, 2011 Virginia Electric and Power Company	Jun. 30, 2012 Virginia Electric and Power Company	Jun. 30, 2011 Virginia Electric and Power Company
Net deferred gains (losses) on derivative-hedging activities, tax	$ (1)	$ (7)	$ (81)	$ 51	$ 2	$ 0	$ 2	$ 0
Changes in unrealized net gains (losses) on investment securities, tax	16	(2)	(41)	(27)	1	0	(5)	(3)
Changes in net unrecognized pension and other postretirement benefit costs, tax	(1)	1	(1)	(16)
Net derivative (gains) losses-hedging activities, tax	11	10	23	5	0	1	(1)	1
Net realized gains on investment securities, tax	3	2	10	4	0	0	1	0
Net pension and other postretirement benefit costs, tax	$ (8)	$ (9)	$ (17)	$ (11)