v2.4.0.6

Acquisitions and Divestitures Sale of Riverside Energy Center (Details) (USD $) In Millions, unless otherwise specified |  |  | 9 Months Ended
--- | --- | --- | ---
Sep. 30, 2012 MW | Dec. 31, 2011 MW | Sep. 30, 2012 Riverside Energy Center [Member] MW
Business Acquisition [Line Items] |  |  |
Power generation capacity | 10,500 | 11,391 | 603
Proceeds from Sale of Productive Assets |  |  | $ 392
Assets | 16,593 | 17,371 | 436
Liabilities | 12,479 | 13,007 | 1
Working capital |  |  | $ 42

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