v2.3.0.15

Derivative Instruments (Details 1) (USD $) In Millions, unless otherwise specified | Sep. 30, 2011 | Dec. 31, 2010
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Net forward notional buy (sell) line items [Abstract] |  |  |  |
Nonmonetary notional amounts - Power (MWh) | (38,000,000) |  | (50,000,000) |
Nonmonetary notional amounts - Natural Gas (MMBtu) | 124,000,000 |  | 31,000,000 |
Interest rate swaps | $ 5,448 | [1] | $ 6,171 | [1]
[1] | Approximately $4.1 billion and $3.3 billion at September 30, 2011 and December 31, 2010, respectively, related to variable rate debt that was converted to fixed rate debt in 2011 and 2010.

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- Definition Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959 + Details
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