v3.19.1
Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) - USD ($)
Mar. 31, 2019
Dec. 31, 2018
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net [1] $ (36,000,000) $ (141,000,000)
Power Contracts [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net [2] 83,000,000 36,000,000
Power Contracts [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 2.20 2.12
Power Contracts [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 208.95 227.98
Natural Gas [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net (4,000,000) (73,000,000)
Natural Gas [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 0.03 0.75
Natural Gas [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information 10.00 8.87
Power Congestion Products [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Derivative, Fair Value, Net 23,000,000 26,000,000
Power Congestion Products [Member] | Minimum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information (6.48) (11.71)
Power Congestion Products [Member] | Maximum [Member]    
Fair Value Measurements Inputs and Valuation Techniques    
Fair Value Inputs Quantitative Information $ 8.24 $ 11.88
[1] At March 31, 2019 and December 31, 2018, we had $187 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] (1)Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy.