Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements and Derivatives - Derivatives measured at fair value and disclosed by balance sheet location (Details)

v3.19.2
Fair Value Measurements and Derivatives - Derivatives measured at fair value and disclosed by balance sheet location (Details) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value $ 26,237 $ 12,125
Derivative liabilities, fair value 140,682 116,352
Designated as Hedging Instrument    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 25,693 17,217
Derivative liabilities, fair value 149,563 117,879
Derivative Contracts Not Designated as Hedging Instruments    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 2,315 0
Derivative liabilities, fair value 0 0
Fuel contracts | Designated as Hedging Instrument | Prepaid expenses and other assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 11,395 2,583
Derivative liabilities, fair value 5,692 1
Fuel contracts | Designated as Hedging Instrument | Other long-term assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 10,085 197
Derivative liabilities, fair value 3,189 29
Fuel contracts | Designated as Hedging Instrument | Accrued expenses and other liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 1,173
Derivative liabilities, fair value 7,154 19,547
Fuel contracts | Designated as Hedging Instrument | Other long-term liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 1,211 933
Derivative liabilities, fair value 13,196 51,184
Fuel contracts | Derivative Contracts Not Designated as Hedging Instruments | Prepaid expenses and other assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 2,315 0
Derivative liabilities, fair value 0 0
Foreign currency contracts | Designated as Hedging Instrument | Prepaid expenses and other assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 2,442 5,285
Derivative liabilities, fair value 0 1,497
Foreign currency contracts | Designated as Hedging Instrument | Other long-term assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 3,514
Derivative liabilities, fair value 0 0
Foreign currency contracts | Designated as Hedging Instrument | Accrued expenses and other liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 517 112
Derivative liabilities, fair value 38,713 5,145
Foreign currency contracts | Designated as Hedging Instrument | Other long-term liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 43 2,874
Derivative liabilities, fair value 76,013 40,476
Interest rate contracts | Designated as Hedging Instrument | Prepaid expenses and other assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 519
Derivative liabilities, fair value 0 0
Interest rate contracts | Designated as Hedging Instrument | Other long-term assets    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 27
Derivative liabilities, fair value 0 0
Interest rate contracts | Designated as Hedging Instrument | Accrued expenses and other liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 0
Derivative liabilities, fair value 3,156 0
Interest rate contracts | Designated as Hedging Instrument | Other long-term liabilities    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 0 0
Derivative liabilities, fair value 2,450 0
Total derivatives    
Derivatives, Fair Value [Line Items]    
Derivative assets, fair value 28,008 17,217
Derivative liabilities, fair value $ 149,563 $ 117,879