Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Loss Carryforwards [Line Items]
Deferred tax liability, recapture of credits claimed in prior years that would result on completion of sale	$ 14
Reductions of deferred tax assets from the enactment of the Patient Protection and Affordable Care Act			57
Unrecognized tax benefits that would impact effective tax rate	167	184	133
Change in unrecognized tax benefits	1	51	(38)
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	1,100
Tax credits	26
Accrual for interst on tax underpayments and overpayments	10
Federal | Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Expiration of statutes of limitations	65
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	1,400
Carryforwards valuation allowance	857
General Business | State
Operating Loss Carryforwards [Line Items]
Tax credits	96
Investment Credit That Expires In 2014 | State
Operating Loss Carryforwards [Line Items]
Tax credits	28
Tax credit carryforward valuation allowance	21
Fairless | State
Operating Loss Carryforwards [Line Items]
Reduction of valuation allowance	20
Brayton Point | State
Operating Loss Carryforwards [Line Items]
Reduction of valuation allowance	14
Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Reductions of deferred tax assets from the enactment of the Patient Protection and Affordable Care Act			17
Unrecognized tax benefits that would impact effective tax rate	13	20	14
Change in unrecognized tax benefits	(1)	(6)	(1)
Virginia Electric and Power Company | Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	220
Virginia Electric and Power Company | Federal | Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Expiration of statutes of limitations	$ 35