Fair Value Measurements and Derivative Instruments - Balance Sheet (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Asset Derivatives
Asset Derivatives		$ 46,367	$ 39,994
Liability Derivatives
Liability Derivatives		363,955	257,728
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	46,367	34,990
Liability Derivatives
Liability Derivatives	[1]	331,932	255,005
Notional Disclosures
Carrying Amount of the Hedged Liabilities		719,553	715,234
Cumulative amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Liabilities		19,555	(1,301)
Not Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives		0	5,004
Liability Derivatives
Liability Derivatives		32,023	2,723
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	19,465	11
Interest rate swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	141,822	64,168
Foreign currency forward contracts | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	16,699	9,380
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	10,203	0
Liability Derivatives
Liability Derivatives	[1]	43,089	75,260
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	29,187	64,711
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
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]	39,808	16,901
Fuel swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	78,026	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		30,578	295
Fuel swaps | Not Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives		$ 1,445	$ 9

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