Preferred Stock of Subsidiaries (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Disclosure Preferred Stock Of Subsidiaries Details [Abstract]
Preferred stock liquidation preference per share	$ 100
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	7.10%
Total	$ 93	$ 93
PEC
Preferred Stock Outstanding [Line Items]
Total	59	59
PEC | Preference Stock
Preferred Stock Outstanding [Line Items]
Shares authorized	10,000,000	10,000,000
PEC | Cumulative | $5 Preferred Stock
Preferred Stock Outstanding [Line Items]
Preferred stock dividend per share amount	$ 5.00	$ 5.00
Shares authorized	300,000	300,000
Share outstanding	236,997	236,997
Redemption price	$ 110.00	$ 110.00
Total	24	24
PEC | Cumulative | Serial Preferred Stock
Preferred Stock Outstanding [Line Items]
Shares authorized	20,000,000	20,000,000
PEC | Cumulative | Serial Preferred Stock | $4.20 Serial Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend per share amount	$ 4.20	$ 4.20
Share outstanding	100,000	100,000
Redemption price	$ 102.00	$ 102.00
Total	10	10
PEC | Cumulative | Serial Preferred Stock | $5.44 Serial Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend per share amount	$ 5.44	$ 5.44
Share outstanding	249,850	249,850
Redemption price	$ 101.00	$ 101.00
Total	25	25
PEC | Cumulative | Preferred Stock A
Preferred Stock Outstanding [Line Items]
Shares authorized	5,000,000	5,000,000
PEF
Preferred Stock Outstanding [Line Items]
Total	34	34
PEF | Preference Stock
Preferred Stock Outstanding [Line Items]
Par Value	$ 100	$ 100
Shares authorized	1,000,000	1,000,000
PEF | Cumulative | Preferred Stock A
Preferred Stock Outstanding [Line Items]
Shares authorized	5,000,000	5,000,000
PEF | Cumulative | Preferred Stock
Preferred Stock Outstanding [Line Items]
Par Value	$ 100	$ 100
Shares authorized	4,000,000	4,000,000
PEF | Cumulative | Preferred Stock | 4.00% $100 par value Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	4.00%	4.00%
Par Value	$ 100	$ 100
Share outstanding	39,980	39,980
Redemption price	$ 104.25	$ 104.25
Total	4	4
PEF | Cumulative | Preferred Stock | 4.40% $100 par value Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	4.40%	4.40%
Par Value	$ 100	$ 100
Share outstanding	75,000	75,000
Redemption price	$ 102.00	$ 102.00
Total	8	8
PEF | Cumulative | Preferred Stock | 4.58% $100 par value Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	4.58%	4.58%
Par Value	$ 100	$ 100
Share outstanding	99,990	99,990
Redemption price	$ 101.00	$ 101.00
Total	10	10
PEF | Cumulative | Preferred Stock | 4.60% $100 par value Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	4.60%	4.60%
Par Value	$ 100	$ 100
Share outstanding	39,997	39,997
Redemption price	$ 103.25	$ 103.25
Total	4	4
PEF | Cumulative | Preferred Stock | 4.75% $100 par value Preferred
Preferred Stock Outstanding [Line Items]
Preferred stock dividend rate percentage	4.75%	4.75%
Par Value	$ 100	$ 100
Share outstanding	80,000	80,000
Redemption price	$ 102.00	$ 102.00
Total	$ 8	$ 8