Nuclear Innovation North America LLC Developments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012 NINA	Sep. 30, 2011 NINA	Mar. 31, 2011 NINA	Sep. 30, 2011 NINA
Loss Contingencies [Line Items]
Impairment charge on investment	$ 1	$ 3	$ 2	$ 495	$ 11	$ 3	$ 481	$ 495

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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