Fair Value Measurements (Net Change in the Assets and Liabilities Measured at Fair Value on a Recurring Basis and Included in the Level 3 Fair Value Category) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Included in earnings	$ (9)	$ (15)	$ (77)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets still held at the reporting date	0	42	22
Commodity | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets still held at the reporting date	0	42	22
Commodity | Level 3 | Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Beginnning balance	25	(71)	(50)
Included in earnings	(9)	(15)	(77)
Included in other comprehensive income (loss)	1	101	14
Included in regulatory assets/liabilities	(9)	30	(42)
Settlements	(23)	47	88
Transfers out of Level 3	(1)	(67)	(4)
Ending balance	(16)	25	(71)
Commodity | Virginia Electric and Power Company | Level 3 | Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Beginnning balance	2	(28)	14
Included in earnings	(17)	(50)	(45)
Included in regulatory assets/liabilities	(9)	30	(42)
Settlements	17	50	45
Ending balance	$ (7)	$ 2	$ (28)