v2.4.0.8
Assets and Liabilities with Recurring Fair Value Measurements (Textuals) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]          
Balance, beginning of period $ 8 $ 13 $ 14 $ 16  
Included in net income:          
Included in operating revenues (7) [1] 3 [1] (15) [1] 4 [1]  
Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense 0 [2] 0 [2] 6 [2] 0 [2]  
Purchases, issuances and settlements:          
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 0 1 0 1  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances 0 0 0 (1)  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements (3) (3) (6) (5)  
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount 0 0 0 0  
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount 0 0 0 0  
Transfers into level 3 2 [3],[4] 0 [3],[4] 0 [3],[4] 0 [3],[4]  
Transfers out of Level 3 (9) [4],[5] (1) [4],[5] (8) [4],[5] (2) [4],[5]  
Balance, end of period (9) 13 (9) 13  
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) (7) 3 (9) 4  
Assets and Liabilities with Recurring Fair Value Measurements (Textuals) [Abstract]          
Cash Equivalents Included In Cash And Cash Equivalents, Fair Value Disclosure 406   406   889
Cash Equivalents Included In Restricted Cash, Fair Value Disclosure $ 230   $ 230   $ 245
[1] For power contracts and other power-related products, included on our Consolidated Condensed Statements of Operations.
[2] For natural gas contracts, swaps and options, included on our Consolidated Condensed Statements of Operations.
[3] We had $2 million in gains transferred out of level 2 into level 3 for the three months ended June 30, 2014 due to changes in market liquidity in various power markets. There were no transfers out of level 2 into level 3 for the three months ended June 30, 2013 and for each of the six months ended June 30, 2014 and 2013.
[4] We transfer amounts among levels of the fair value hierarchy as of the end of each period. There were no transfers into or out of level 1 for each of the three and six months ended June 30, 2014 and 2013.
[5] We had $9 million and $1 million in gains transferred out of level 3 into level 2 for the three months ended June 30, 2014 and 2013, respectively, and $8 million and $2 million in gains transferred out of level 3 into level 2 for the six months ended June 30, 2014 and 2013, respectively, due to changes in market liquidity in various power markets.