v2.4.0.6

Acquisitions, Divestitures and Discontinued Operations (Textuals) (Details) (USD $) | 12 Months Ended |  |  | 12 Months Ended |  |  |  | 12 Months Ended |  | 12 Months Ended |  | 12 Months Ended |
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Dec. 31, 2012 MW | Dec. 31, 2011 MW | Dec. 31, 2010 | Dec. 08, 2010 | Dec. 31, 2012 Bosque Energy Center [Member] MW | Dec. 31, 2011 Conectiv [Member] | Mar. 02, 2011 Conectiv [Member] MW | Jul. 02, 2010 Conectiv [Member] | Dec. 08, 2010 Broad River and South Point [Member] | Dec. 08, 2010 Broad River [Member] | Dec. 08, 2010 South Point [Member] | Dec. 31, 2012 Riverside Energy Center [Member] MW | Dec. 31, 2012 Broad River Energy Center [Member] MW | Dec. 27, 2012 Broad River Energy Center [Member] | Dec. 31, 2010 Blue Spruce and Rock Mountain [Member] | Dec. 06, 2010 Blue Spruce and Rock Mountain [Member] | Dec. 31, 2010 Freestone Energy Center [Member] | Dec. 08, 2010 Freestone Energy Center [Member]
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Undivided Interest Percentage In Power Plant Asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00%
Cash Proceeds From Sale Of Undivided Interest In Power Plant Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 215,000,000
Business Acquisition, Preexisting Relationship, Gain (Loss) Recognized |  |  |  | 125,000,000 |  |  |  |  | 125,000,000 |  |  |  |  |  |  |  |  |
Business Acquisition, Purchase Price Allocation, Notes Payable and Long-term Debt |  |  |  |  |  |  |  |  | 297,000,000 |  |  |  |  |  |  |  |  |
Variable Interest Entity, Financial or Other Support, Amount | 20,000,000 | 87,000,000 | 46,000,000 |  |  | 110,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Power generation capacity | 8,255 | 11,391 |  |  | 800 |  | 4,491 |  |  |  |  | 603 | 847 |  |  |  |  |
Business Acquisition, Purchase Price Allocation, Assets Acquired |  |  |  |  | 432,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Power Plants Acquired |  |  |  |  |  |  |  | 18 |  |  |  |  |  |  |  |  |  |
Block one power generation capacity |  |  |  |  | 250 |  |  |  |  |  |  |  |  |  |  |  |  |
Block two power generation capacity |  |  |  |  | 550 |  |  |  |  |  |  |  |  |  |  |  |  |
Cap on Environmental Remediation Liabilities Acquired |  |  |  |  |  |  |  | 10,000,000 |  |  |  |  |  |  |  |  |  |
Number of Employees Acquired In Acquisition |  |  |  |  |  |  |  | 130 |  |  |  |  |  |  |  |  |  |
Number Of Employees For Which Pension Obligation Was Reduced |  |  |  |  |  |  |  | 31 |  |  |  |  |  |  |  |  |  |
Proceeds from Subsidiary Project Debt |  |  |  |  |  |  |  | 1,300,000,000 |  |  |  |  |  |  |  |  |  |
Business Acquisition, Cost of Acquired Entity, Purchase Price |  |  |  |  |  |  |  | 1,640,000,000 |  |  |  |  |  |  |  |  |  |
Business Acquisition, Cost of Acquired Entity, Cash Paid |  |  |  |  |  |  |  |  | 40,000,000 |  |  |  |  |  |  |  |  |
Business Acquisition, Purchase Price Allocation, Liabilities Assumed |  |  |  |  |  |  |  |  | 85,000,000 |  |  |  |  |  |  |  |  |
Debt Eliminated In Acquisition |  |  |  |  |  |  |  |  | 212,000,000 |  |  |  |  |  |  |  |  |
Debt Extinguishment Costs Due To Acquisition |  |  |  | 30,000,000 |  |  |  |  |  | 30,000,000 |  |  |  |  |  |  |  |
Impairment Loss Due To Acquisition |  |  |  | 95,000,000 |  |  |  |  |  |  | 95,000,000 |  |  |  |  |  |  |
Proceeds from Sale of Productive Assets |  |  |  |  |  |  |  |  |  |  |  | 402,000,000 | 423,000,000 |  | 739,000,000 |  |  |
Gain (Loss) on Disposition of Assets | 222,000,000 | 0 | 119,000,000 |  |  |  |  |  |  |  |  | 7,000,000 | 215,000,000 |  |  |  | 119,000,000 |
Ownership percentage before divestiture of business |  |  |  |  |  |  |  |  |  |  |  |  |  | 100.00% |  | 100.00% |  |
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal |  |  | $ 209,000,000 |  |  |  |  |  |  |  |  |  |  |  | $ 209,000,000 |  |  |

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