v3.7.0.1

Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) - USD ($) | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Fair Value, Net | $ 139,000,000 | $ 162,000,000
Power Contracts [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Fair Value, Net | 245,000,000 | 360,000,000
Power Contracts [Member] | Minimum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | 7.40 | 9.60
Power Contracts [Member] | Maximum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | 93.77 | 86.34
Natural Gas [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Fair Value, Net | 37,000,000 | 17,000,000
Natural Gas [Member] | Minimum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | 1.62 | 1.95
Natural Gas [Member] | Maximum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | 6.15 | 5.66
Power Congestion Products [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Fair Value, Net | 12,000,000 | 12,000,000
Power Congestion Products [Member] | Minimum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | (7.92) | (7.52)
Power Congestion Products [Member] | Maximum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information | $ 5.13 | $ 13.62

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