Organization, Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Difference between total transfer price and the net book value of the generation-related assets	986
Nuclear Production [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P60Y
Pumped Storage Facilities [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P76Y
Minimum [Member] | General Plant Assets [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P3Y
Minimum [Member] | Fossil Production [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P10Y
Maximum [Member] | General Plant Assets [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P20Y
Maximum [Member] | Fossil Production [Member]
Organization Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	P79Y