XML 52 R39.htm IDEA: XBRL DOCUMENT v3.7.0.1
Fair Value Measurements - Quantative Information about Level 3 Fair Value (Details) - Option Model - Implied Volatility - Fuel derivatives
Mar. 31, 2017
Second quarter 2017  
Quantitative Information About Level 3  
Fair Value Measurement Range, Minimum 15.00%
Fair Value Measurement Range, Maximum 29.00%
Third quarter 2017  
Quantitative Information About Level 3  
Fair Value Measurement Range, Minimum 21.00%
Fair Value Measurement Range, Maximum 30.00%
Fourth quarter 2017  
Quantitative Information About Level 3  
Fair Value Measurement Range, Minimum 22.00%
Fair Value Measurement Range, Maximum 30.00%
2018  
Quantitative Information About Level 3  
Fair Value Measurement Range, Minimum 20.00%
Fair Value Measurement Range, Maximum 29.00%
2019  
Quantitative Information About Level 3  
Fair Value Measurement Range, Minimum 17.00%
Fair Value Measurement Range, Maximum 24.00%