v3.19.2
Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) - USD ($)
Jun. 30, 2019
Dec. 31, 2018
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net [1] $ 131,000,000 $ (141,000,000)
Power Contracts [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net [2] 190,000,000 36,000,000
Power Contracts [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 7.09 2.12
Power Contracts [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 123.34 227.98
Natural Gas [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net 6,000,000 (73,000,000)
Natural Gas [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 0.61 0.75
Natural Gas [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 9.75 8.87
Power Congestion Products [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net 18,000,000 26,000,000
Power Congestion Products [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information (8.63) (11.71)
Power Congestion Products [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information $ 11.48 $ 11.88
[1] At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.
[2] Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy.