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Debt and Other Obligations - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2021	Sep. 17, 2020
Debt Instrument [Line Items]
Commitment and other fees	$ 2,243	$ 1,106
Amortization of deferred financing costs	13,282	10,751
Total	155,611	134,520
Accretion of convertible debt and 8.00% senior secured notes	1,272	10,138	$ 0
Secured Debt
Debt Instrument [Line Items]
Accretion of convertible debt and 8.00% senior secured notes	1,300	500
Interest expense	$ 50,600	$ 19,500
Secured Debt \| 8.00% senior secured notes due in 2025
Debt Instrument [Line Items]
Stated interest rate percentage	8.00%	8.00%		8.00%	8.00%
Interest expense	$ 51,897	$ 19,953
Fixed-rate term loans
Debt Instrument [Line Items]
Interest expense	42,765	43,591
Unsecured term loans due through 2031
Debt Instrument [Line Items]
Interest expense	1,168	409
2015-1 EETC Class A
Debt Instrument [Line Items]
Interest expense	12,781	13,730
2015-1 EETC Class B
Debt Instrument [Line Items]
Interest expense	2,669	3,027
2015-1 EETC Class C
Debt Instrument [Line Items]
Interest expense	3,988	4,565
2017-1 EETC Class AA
Debt Instrument [Line Items]
Interest expense	6,938	7,412
2017-1 EETC Class A
Debt Instrument [Line Items]
Interest expense	2,501	2,672
2017-1 EETC Class B
Debt Instrument [Line Items]
Interest expense	2,189	2,445
2017-1 EETC Class C
Debt Instrument [Line Items]
Interest expense	4,367	4,379
Convertible notes
Debt Instrument [Line Items]
Interest expense	6,997	14,905
Accretion of convertible debt and 8.00% senior secured notes		9,600
Interest expense		5,300
Revolving Credit Facility
Debt Instrument [Line Items]
Interest expense	1,733	5,380
Finance leases
Debt Instrument [Line Items]
Interest expense	$ 93	$ 195