Debt and Credit Facilities - Covenants and Default Provisions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2011 AdjustedNetEarningsPerAnnualInterestRequirement	Dec. 31, 2011 AdjustedNetEarningsPerAnnualInterestRequirement
Financial Covenants [Line Items]
Debt instrument, covenant description		All of the credit facilities include a defined maximum total debt to total capitalization ratio (leverage).
Collateralized obligations
Refund to customers recorded as a reduction to revenue	$ 288
Ratio of adjusted net earnings to annual interest requirement	2.0	2.0
Parent
Financial Covenants [Line Items]
Maximum ratio		68.00%
Actual ratio		58.00%
Cross-default provisions
Cross-default provisions for defaults of indebtedness in excess of thresholds	50	50
Range of default amounts that contain cross-default provisions, bottom of range	25	25
Range of default amounts that contain cross-default provisions, top of range	50	50
Potential accelerated payment required by debt holder in event of indenture cross-default provisions being triggered	4,000	4,000
PEC
Financial Covenants [Line Items]
Maximum ratio		65.00%
Actual ratio		46.00%
Cross-default provisions
Cross-default provisions for defaults of indebtedness in excess of thresholds	35	35
Retained earnings note disclosure
Ratio of common stock equity to total capital		57.60%
Collateralized obligations
Secured debt	3,694	3,694
PEC | Mortgage Indenture
Retained earnings note disclosure
Retained earnings, restrictions		as long as any first mortgage bonds are outstanding, cash dividends and distributions on its common stock and purchases of its common stock are restricted to aggregate net income available for PEC since December 31, 1948, plus $3 million, less the amount of all preferred stock dividends and distributions, and all common stock purchases, since December 31, 1948.
PEC | Articles Of Incorporation
Retained earnings note disclosure
Retained earnings, restrictions		so long as any shares of preferred stock are outstanding, the aggregate amount of cash dividends or distributions on common stock since December 31, 1945, including the amount then proposed to be expended, shall be limited to 75 percent of the aggregate net income available for common stock if common stock equity falls below 25 percent of total capitalization, as defined by PEC’s Articles of Incorporation, and to 50 percent if common stock equity falls below 20 percent. PEC’s Articles of Incorporation also provide that cash dividends on common stock shall be limited to 75 percent of the current year’s net income available for dividends if common stock equity falls below 25 percent of total capitalization, and to 50 percent if common stock equity falls below 20 percent.
PEF
Financial Covenants [Line Items]
Maximum ratio		65.00%
Actual ratio		51.00%
Cross-default provisions
Cross-default provisions for defaults of indebtedness in excess of thresholds	35	35
Retained earnings note disclosure
Ratio of common stock equity to total capital		50.90%
Collateralized obligations
Secured debt	$ 4,341	4,341
PEF | Mortgage Indenture
Retained earnings note disclosure
Retained earnings, restrictions		as long as any first mortgage bonds are outstanding, it will not pay any cash dividends upon its common stock, or make any other distribution to the stockholders, except a payment or distribution out of net income of PEF subsequent to December 31, 1943.
PEF | Articles Of Incorporation
Retained earnings note disclosure
Retained earnings, restrictions		so long as any shares of preferred stock are outstanding, no cash dividends or distributions on common stock shall be paid, if the aggregate amount thereof since April 30, 1944, including the amount then proposed to be expended, plus all other charges to retained earnings since April 30, 1944, exceeds all credits to retained earnings since April 30, 1944, plus all amounts credited to capital surplus after April 30, 1944, arising from the donation to PEF of cash or securities or transfers of amounts from retained earnings to capital surplus. PEF’s Articles of Incorporation also provide that cash dividends on common stock shall be limited to 75 percent of the current year’s net income available for dividends if common stock equity falls below 25 percent of total capitalization, as defined by PEF’s Articles of Incorporation, and to 50 percent if common stock equity falls below 20 percent.