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Fair Value Measurements - Quantative Information about Level 3 Fair Value (Details) - Option Model - Implied Volatility - Fuel derivatives | Jun. 30, 2016
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Third Quarter 2016 |
Quantitative Information About Level 3 [Line Items] |
Fair Value Measurement Range, Minimum | 20.00%
Fair Value Measurement Range, Maximum | 34.00%
Fourth Quarter 2016 |
Quantitative Information About Level 3 [Line Items] |
Fair Value Measurement Range, Minimum | 27.00%
Fair Value Measurement Range, Maximum | 36.00%
2017 |
Quantitative Information About Level 3 [Line Items] |
Fair Value Measurement Range, Minimum | 27.00%
Fair Value Measurement Range, Maximum | 39.00%
2018 |
Quantitative Information About Level 3 [Line Items] |
Fair Value Measurement Range, Minimum | 23.00%
Fair Value Measurement Range, Maximum | 32.00%

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