Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements and Derivatives (Detail Textuals)

v3.19.1
Fair Value Measurements and Derivatives (Detail Textuals)
Metric_Ton in Thousands, $ in Millions, € in Billions
3 Months Ended
Mar. 31, 2019
USD ($)
Metric_Ton
Mar. 31, 2019
EUR (€)
Metric_Ton
Dec. 31, 2018
USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Fair value of long-term debt $ 6,686.1   $ 6,601.9
Fair value of long-term debt in excess of carrying value $ 30.3   $ 8.4
Fuel swaps      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Derivative maturing date Dec. 31, 2021    
Projected fuel purchases | Metric_Ton 1,200 1,200  
Fuel swaps | Derivative Contracts Not Designated as Hedging Instruments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Projected fuel purchases | Metric_Ton 29 29  
Foreign Currency Forward Contracts      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Notional amount of derivatives $ 2,700.0 € 2.4  
Interest Rate Swap      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Notional amount of derivatives $ 1,200.0