Fair Value Measurements and Derivative Instruments - Balance Sheet (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Asset Derivatives
Asset Derivatives		$ 40,960	$ 39,994
Liability Derivatives
Liability Derivatives		557,492	257,728
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	40,960	34,990
Liability Derivatives
Liability Derivatives	[1]	494,047	255,005
Notional Disclosures
Carrying Amount of the Hedged Liabilities		736,885	715,234
Cumulative amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Liabilities		20,029	(1,301)
Not Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives		0	5,004
Liability Derivatives
Liability Derivatives		63,445	2,723
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	19,787	11
Interest rate swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	113,312	64,168
Foreign currency forward contracts | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	21,173	9,380
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	0	0
Liability Derivatives
Liability Derivatives	[1]	75,862	75,260
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	119,303	64,711
Foreign currency forward contracts | Not Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives		0	0
Foreign currency forward contracts | Not Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives		0	3,186
Liability Derivatives
Liability Derivatives		0	2,419
Foreign currency forward contracts | Not Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives		0	0
Fuel swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	0	8,677
Fuel swaps | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	0	16,922
Liability Derivatives
Liability Derivatives	[1]	66,098	16,901
Fuel swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	119,472	33,965
Fuel swaps | Not Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives		0	175
Fuel swaps | Not Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives		0	1,643
Liability Derivatives
Liability Derivatives		61,347	295
Fuel swaps | Not Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives		$ 2,098	$ 9

[1] Accounting Standard Codification 815-20 “Derivatives and Hedging.”