Risk Management and Fair Values (Schedules Of Valuation Techniques) (Details) (Imported) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Effect of Significant Unobservable Inputs on Fair Value of Electricity Options	$ 28
Effect of Significant Unobservable Inputs on Fair Value of Electricity Swaps	13
Fair Value of Electricity Options	92
Fair Value of Electricity Swaps	$ 206
Maximum [Member]
Range From Average Percentage for Electricity Options	12.00%
Range from Average Percentage for Fair Value of Electricity Swaps	3.00%