Nature of Operations and Summary of Significant Accounting Policies - Flying Agreements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Agreements with other airlines
Percentage of ASMs flown under fixed-fee arrangements	86.50%	88.00%	84.30%
EAS contract term	2 years
Percentage of ASMs flown under pro-rate arrangements	13.50%	12.00%	15.70%
Rental income under operating leases
Operating lease revenue	$ 47,554	$ 48,714	$ 46,532
Operating lease revenue relating to variable lease payments	18,420	17,050	19,998
Total operating revenues	2,935,432	3,004,925	2,713,491
Future minimum rental income
2024	46,119
2025	41,172
2026	35,630
2027	35,586
2028	35,024
Thereafter	53,122
Total future minimum rental income under operating leases	246,653
Deferred revenue recognized	12,600	18,700
Unbilled revenue recognized	(12,601)	11,491	8,404
Unbilled revenue	7,300	19,900
Deferred revenue	374,600	144,700
Deferred revenue in other current liabilities	61,000	5,200
Deferred revenue in other long-term liabilities	313,600	139,500
Property and equipment and related assets	5,482,967	5,548,480
Deferred recognizing revenue	229,862	40,812	(6,832)
Accounts receivable	82,900	100,500
Gross receivables current	86,100
Gross receivables Non-current	199,800
Balance	37,385	41,976	46,225
Adjustments to credit loss reserves	(185)	(4,591)	(4,249)
Write-offs charged against allowance	(18,501)
Balance	18,699	37,385	41,976
Other Noncurrent Liabilities
Future minimum rental income
Deferred lease revenue	78,500	22,100
Other Current Assets
Future minimum rental income
Unbilled revenue	1,200	9,900
Other Noncurrent Assets
Future minimum rental income
Unbilled revenue	6,100	$ 10,000
Capacity Purchase Agreements
Future minimum rental income
Deferred revenue	$ 151,400
United | United Express Agreements
Future minimum rental income
Agreement term	2 years 8 months 12 days
United | United Express Prorate Agreement
Future minimum rental income
Notice period for termination of agreement	120 days
Delta
Future minimum rental income
Number of aircraft | aircraft	135
Delta | Delta Connection Prorate Agreement
Future minimum rental income
Notice period for termination of agreement	30 days
Delta | Delta Connection Agreements
Future minimum rental income
Agreement term		4 years 9 months 18 days
American | American Capacity Purchase Agreement
Future minimum rental income
Agreement term	3 years 1 month 6 days
Alaska | Alaska Capacity Purchase Agreement
Future minimum rental income
Agreement term	7 years 6 months
Jet aircraft and spare engines leased to third parties
Future minimum rental income
Property and equipment and related assets	$ 216,000
CRJ 200
Future minimum rental income
Number of seats on aircraft | aircraft	50
CRJ 200 | United | United Express Agreements
Future minimum rental income
Number of aircraft | aircraft	70
CRJ 200 | United | United Express Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft	19
CRJ 700 | Minimum
Future minimum rental income
Number of seats on aircraft | aircraft	65
CRJ 700 | Maximum
Future minimum rental income
Number of seats on aircraft | aircraft	76
CRJ 700 | United | United Express Agreements
Future minimum rental income
Number of aircraft | aircraft	19
CRJ 700 | Delta | Delta Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft	5
CRJ 700 | Delta | Delta Connection Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft	4
CRJ 700 | American | American Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft	90
CRJ 900 | Minimum
Future minimum rental income
Number of seats on aircraft | aircraft	65
CRJ 900 | Maximum
Future minimum rental income
Number of seats on aircraft | aircraft	76
CRJ 900 | Delta | Delta Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft	35
CRJ 900 | Delta | Delta Connection Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft	6
E175
Agreements with other airlines
2024 | aircraft	5
2025 | aircraft	8
2026 | aircraft	8
Total | aircraft	21
E175 | Minimum
Future minimum rental income
Number of seats on aircraft | aircraft	65
E175 | Maximum
Future minimum rental income
Number of seats on aircraft | aircraft	76
E175 | United | United Express Agreements
Agreements with other airlines
2024 | aircraft	4
2025 | aircraft	7
2026 | aircraft	8
Total | aircraft	19
Future minimum rental income
Number of aircraft | aircraft	90
E175 | Delta | Delta Capacity Purchase Agreement
Agreements with other airlines
2024 | aircraft	1
Total | aircraft	1
Future minimum rental income
Number of aircraft | aircraft	85
E175 | American | American Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft	20
E175 | Alaska | Alaska Capacity Purchase Agreement
Agreements with other airlines
2025 | aircraft	1
Total | aircraft	1
Flying agreements
Rental income under operating leases
Total operating revenues	$ 2,834,397	$ 2,899,837	2,615,076
Future minimum rental income
Accounts receivable	73,600	73,700
Capacity purchase agreements flight operations revenue (non-lease component)
Rental income under operating leases
Total operating revenues	1,976,743	2,028,308	1,678,219
Capacity purchase agreements fixed aircraft lease revenue
Rental income under operating leases
Total operating revenues	296,047	504,529	527,173
Capacity purchase agreements variable aircraft lease revenue
Rental income under operating leases
Total operating revenues	180,218	17,664
Prorate agreements and SWC revenue
Rental income under operating leases
Total operating revenues	381,389	349,336	409,684
Airport customer service and other revenue
Rental income under operating leases
Total operating revenues	35,061	39,324	31,885
Lease, airport services and other.
Rental income under operating leases
Total operating revenues	$ 101,035	$ 105,088	$ 98,415