XML 65 R50.htm IDEA: XBRL DOCUMENT v3.5.0.2
Fair Value Measurements (Details 2) - Level 3
$ in Millions
 9 Months Ended
Sep. 30, 2016
USD ($)
MWh
$ / MWh
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
FTRs      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ $ 6 $ (5) $ 25
FTRs | FES      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ 2 (6) 14
NUG contracts      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ (118) $ (136) $ (151)
Model | FTRs      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ 6    
Model | FTRs | FES      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ 2    
Model | NUG contracts      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value | $ $ (118)    
Model | Minimum | FTRs      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) (2.20)    
Model | Minimum | FTRs | FES      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) (2.20)    
Model | Minimum | NUG contracts      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, Power (in MWH) | MWh 400    
Fair Value Inputs, Power, Regional Prices (in $/MWH) 30.90    
Model | Maximum | FTRs      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) 7.60    
Model | Maximum | FTRs | FES      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) 7.60    
Model | Maximum | NUG contracts      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, Power (in MWH) | MWh 3,207,000    
Fair Value Inputs, Power, Regional Prices (in $/MWH) 35.30    
Model | Weighted Average | FTRs      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) 1.00    
Model | Weighted Average | FTRs | FES      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, RTO Auction Clearing Prices (in $/MWH) 0.70    
Model | Weighted Average | NUG contracts      
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]      
Fair Value Inputs, Power (in MWH) | MWh 661,000    
Fair Value Inputs, Power, Regional Prices (in $/MWH) 32.10