v3.19.3
Assets and Liabilities with Recurring Fair Value Measurements (Textuals) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Fair Value Measurement [Domain]          
Fair Value Disclosures [Abstract]          
Cash and Cash Equivalents, at Carrying Value $ 187   $ 187   $ 23
Restricted Cash and Cash Equivalents 172   172   145
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs 227 $ 131 (8) $ 197  
Included in operating revenues [1] 20 (99) 151 (84)  
Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense [2] 0 18 2 27  
Amount of Change in Collateral of Financial Instruments Classified as Derivative Asset (Liability) (1) 0 0 0  
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases 0 4 3 12  
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Issues 0 0 (1) 0  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements (23) 37 68 (56)  
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount 0 0 0 0  
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount 0 0 0 0  
Transfers into level 3 [3],[4] 7 (1) 10 0  
Transfers out of Level 3 [4],[5] (23) (2) (18) (8)  
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs 207 88 207 88  
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) 20 $ (81) 153 $ (57)  
Cash and Cash Equivalents, at Carrying Value 792   792   205
Restricted Cash and Cash Equivalents 407   407   201
Fair Value, Inputs, Level 1 [Member]          
Fair Value Disclosures [Abstract]          
Derivative, Collateral, Right to Reclaim Cash, Net 88   88   (1)
Fair Value, Inputs, Level 2 [Member]          
Fair Value Disclosures [Abstract]          
Derivative, Collateral, Right to Reclaim Cash, Net 2   2   48
Fair Value, Inputs, Level 3 [Member]          
Fair Value Disclosures [Abstract]          
Derivative, Collateral, Right to Reclaim Cash, Net $ 0   $ 0   $ 0
[1] For power contracts and other power-related products, included on our Consolidated Condensed Statements of Operations.
[2] For natural gas and power contracts, swaps and options, included on our Consolidated Condensed Statements of Operations.
[3] We had $7 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the three months ended September 30, 2019 and 2018, respectively, and $10 million in gains and nil transferred out of level 2 into level 3 for the nine months ended September 30, 2019 and 2018, respectively, due to changes in market liquidity in various power markets.
[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 nine months ended September 30, 2019 and 2018.
[5] We had $23 million and $2 million in gains transferred out of level 3 into level 2 for the three months ended September 30, 2019 and 2018, respectively, and $18 million and $8 million in gains transferred out of level 3 into level 2 for the nine months ended September 30, 2019 and 2018, respectively, due to changes in market liquidity in various power markets.