v2.4.0.6

Assets and Liabilities with Recurring Fair Value Measurements (Textuals) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Balance, beginning of period | $ 17 |  | $ 30 |  | $ 38 |
Included in net income: |  |  |  |  |  |
Included in operating revenues | 8 | [1] | 5 | [1] | 7 | [1]
Included in fuel and purchased energy expense | 0 | [2] | 0 | [2] | 0 | [2]
Included in OCI | 0 |  | 2 |  | 2 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 3 |  | 0 |  | 0 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issues | (1) |  | 0 |  | 0 |
Purchases, issuances and settlements: |  |  |  |  |  |
Settlements | (11) |  | (18) |  | (20) |
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount | 0 |  | 0 |  | 0 |
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount | 0 |  | 0 |  | 0 |
Transfers into level 3 | 0 | [3],[4] | (2) | [3],[4] | 0 | [3],[4]
Transfers out of level 3 | 0 | [4],[5] | 0 | [4],[5] | 3 |
Balance, end of period | 16 |  | 17 |  | 30 |
Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Change in Unrealized Gain (Loss) Held At Period End | 8 | [2] | 5 | [2] | 7 | [2]
Assets and Liabilities with Recurring Fair Value Measurements (Textuals) [Abstract] |  |  |  |  |  |
Cash Equivalents Included In Cash And Cash Equivalents, Fair Value Disclosure | 1,274 |  | 1,249 |  |  |
Cash Equivalents Included In Restricted Cash, Fair Value Disclosure | $ 228 |  | $ 166 |  |  |
[1] | For power contracts and Heat Rate swaps and options, included on our Consolidated Statements of Operations.
[2] | For natural gas contracts, swaps and options, included on our Consolidated Statements of Operations.
[3] | There were no significant transfers into level 3 for the years ended December 31, 2012 and 2010. We had $2 million in losses transferred out of level 2 into level 3 for the year ended December 31, 2011 due to changes in market liquidity in various power and natural gas markets.
[4] | We transfer amounts among levels of the fair value hierarchy as of the end of each period. There were no significant transfers into/out of level 1 during the years ended December 31, 2012, 2011 and 2010.
[5] | We had no significant transfers out of level 3 for the years ended December 31, 2012 and 2011. There were $3 million in losses transferred out of level 3 into level 2 for the year ended December 31, 2010 due to changes in market liquidity in various power markets.

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- Definition Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense + References No definition available. + Details
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- Definition Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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