Commitments and Contingencies Commitments and Contingencies (Merchant Generation Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other operations and maintenance		$ 3,483	$ 3,724	$ 3,712
Severance Costs	206
Employee Severance [Member]
Other operations and maintenance		17
Other Operations And Maintenance After Tax		$ 11

The charge against earnings in the period for known and estimated costs of termination benefits provided to current employees that are involuntarily terminated under a benefit arrangement associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding costs or losses pertaining to an entity newly acquired in a business combination or a discontinued operation as defined by generally accepted accounting principles and costs associated with one-time termination benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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+ Details