Fair Value Measurements and Derivative Instruments - Balance Sheet (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Asset Derivatives
Asset Derivatives		$ 72,900	$ 108,539
Liability Derivatives
Liability Derivatives		196,293	259,705
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	69,735	107,705
Liability Derivatives
Liability Derivatives	[1]	177,905	240,573
Notional Disclosures
Carrying Amount of the Hedged Liabilities		662,822	700,331
Cumulative amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Liabilities		14,582	17,512
Not Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives		3,165	834
Liability Derivatives
Liability Derivatives		18,388	19,132
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	16,152	17,271
Interest rate swaps | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives		149	261
Liability Derivatives
Liability Derivatives		0	0
Interest rate swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	97,981	144,653
Foreign currency forward contracts | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	5,842	20,836
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	30,268	63,894
Liability Derivatives
Liability Derivatives	[1]	26,903	13,294
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	23,032	7,306
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		1,201	0
Liability Derivatives
Liability Derivatives		4,284	160
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]	2,225	350
Fuel swaps | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	15,099	5,093
Liability Derivatives
Liability Derivatives	[1]	9,135	25,203
Fuel swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	20,854	50,117
Fuel swaps | Not Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives		29	0
Fuel swaps | Not Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives		1,935	834
Liability Derivatives
Liability Derivatives		13,076	18,028
Fuel swaps | Not Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives		$ 1,028	$ 944

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