Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements and Derivatives (Detail Textuals)

v3.5.0.2
Fair Value Measurements and Derivatives (Detail Textuals)
$ in Millions, € in Billions
6 Months Ended
Jun. 30, 2016
USD ($)
Metric_Ton
Jun. 30, 2016
EUR (€)
Metric_Ton
Dec. 31, 2015
USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Fair value of long-term debt $ 6,700.0   $ 6,500.0
Fair value of long-term debt in excess of carrying value $ 11.5   $ 6.6
Fuel Swaps      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Derivative maturing date Dec. 31, 2019    
Projected fuel purchases | Metric_Ton 1,800,000 1,800,000  
Fuel Swaps | Not Designated as Hedging Instrument      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Projected fuel purchases | Metric_Ton 22,000 22,000  
Foreign Currency Forward Contracts      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Notional amount of derivatives $ 2,600.0 € 2.3  
Interest Rate Swap      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Notional amount of derivatives $ 366.3