Long-term Debt (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) aircraft	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Current portion long-term debt	$ 413,703	$ 395,371
Current portion of unamortized debt issue cost, net	(3,579)	(3,573)
Current portion of long-term debt, net of debt issue costs	410,124	391,798
Long-term debt, net of current maturities	2,818,727	2,745,567
Long-term portion of unamortized debt issue cost, net	(27,453)	(28,147)
Long-term debt, net of current maturities and debt issue costs	2,791,274	2,717,420
Total long-term debt (including current portion)	3,232,430	3,140,938
Total unamortized debt issue cost, net	(31,032)	(31,720)
Total long-term debt, net of debt issue costs	3,201,398	3,109,218
Long-term debt	3,201,398	$ 3,109,218
Amount outstanding	0
Maximum borrowing capacity	100,000
Current borrowing capacity	68,600
Letters of credit and surety bonds
Debt Instrument [Line Items]
Letters of credit and surety bonds outstanding with various banks and surety institutions	61,400
Letters of credit
Debt Instrument [Line Items]
Amount outstanding	$ 31,400
Promissory note
Debt Instrument [Line Items]
Debt instrument, term	3 years
Interest rate (as a percent)	3.60%
Principal amount	$ 102,900
E175
Debt Instrument [Line Items]
Number of aircraft delivered | aircraft	4
Purchase of aircraft financed through long-term debt	$ 82,800
Minimum | E175
Debt Instrument [Line Items]
Debt instrument, term	5 years
Maximum | E175
Debt Instrument [Line Items]
Debt instrument, term	10 years