v3.6.0.2
Assets and Liabilities with Recurring Fair Value Measurements (Textuals) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Fair Value Measurement [Domain]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash and Cash Equivalents, at Carrying Value $ 418 $ 906    
Cash Equivalents Included In Restricted Cash, Fair Value Disclosure 188 228    
Balance, beginning of period (46) 85 $ 14  
Included in operating revenues [1] (46) 218 70  
Included in fuel and purchased energy expense [2] 7 (7) 5  
Purchases(3) [3] 426 (70) 6  
Settlements (21) (29) (10)  
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 [4],[5] (4) 0 0  
Transfers out of level 3 [5],[6] 75 (243) 0  
Balance, end of period 399 (46) 85  
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) (39) 211 75  
Cash and Cash Equivalents, at Carrying Value 418 906 717 $ 941
Cash Equivalents Included In Restricted Cash, Fair Value Disclosure 188 228    
Transfer to Level 2 [Member]        
Purchases, issuances and settlements:        
Transfers out of level 3 [5],[6] 75 (4) $ 0  
Transfer to Other Assets [Member]        
Purchases, issuances and settlements:        
Transfers out of level 3 [5],[6]   $ (239)    
Calpine Solutions [Member]        
Purchases, issuances and settlements:        
Purchases(3) [3] $ 421      
[1] For power contracts and other power-related products, included on our Consolidated Statements of Operations.
[2] For natural gas and power contracts, swaps and options, included on our Consolidated Statements of Operations.
[3] During December 2016, we had $421 million in purchases related to the acquisition of Calpine Solutions, formerly Noble Solutions.
[4] We had $4 million in gains transfers out of level 2 into level 3 for the year ended December 31, 2016. There were no transfers out of level 2 into level 3 for the years ended December 31, 2015 and 2014.
[5] 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 during the years ended December 31, 2016, 2015 and 2014.
[6] We had $(75) million in losses and $4 million in gains transferred out of level 3 into level 2 during the years ended December 31, 2016 and 2015, respectively, due to changes in market liquidity in various power markets and $239 million in gains transferred out of level 3 during the year ended December 31, 2015 to other assets following the election of the normal purchase normal sales exemption and the discontinuance of derivative accounting treatment as of the date of this election. There were no transfers out of level 3 for the year ended December 31, 2014.