Operating Revenues (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($) aircraft	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) aircraft item	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Agreements with other airlines
Percentage of ASMs flown under fixed-fee arrangements			85.50%	87.10%
Percentage of ASMs flown under pro-rate arrangements			14.50%	12.90%
Rental income under operating leases
Operating lease fixed revenue	$ 16,697	$ 14,071	$ 32,762	$ 25,670
Operating lease variable revenue	8,526	8,045	15,535	13,114
Total operating revenues	1,035,227	867,118	1,983,682	1,670,732
Future minimum rental income
July 2025 through December 2025	23,040		23,040
2026	41,053		41,053
2027	38,697		38,697
2028	37,818		37,818
2029	36,296		36,296
Thereafter	21,218		21,218
Total future minimum rental income under operating leases	198,122		198,122
Deferred revenue recognized			21,300	6,000
Increase (decrease) in unbilled revenue			5,700	(600)
Increase (decrease) in unbilled lease revenue			2,900
Deferred revenue	309,100		309,100		$ 337,500
Deferred revenue in other current liabilities	105,100		105,100		54,800
Deferred revenue in other long-term liabilities	204,000		204,000		282,700
Unbilled revenue	22,600		22,600		15,100
Property and equipment and related assets	5,681,348		5,681,348		5,587,408
Gross receivables current	159,900		159,900		125,900
Gross receivables Non-current	231,800		231,800		225,200
Balance			15,071
Adjustments to credit loss reserves			10,053
Write-offs charged against allowance			(63)
Balance	25,061		25,061
Other Current Assets
Future minimum rental income
Unbilled revenue	1,100		1,100		1,100
Other Noncurrent Assets
Future minimum rental income
Unbilled revenue	21,500		21,500		$ 14,000
Other Noncurrent Liabilities
Future minimum rental income
Deferred lease revenue	$ 6,000	1,000	$ 6,000	1,000
Minimum
Agreements with other airlines
EAS contract term			2 years
Maximum
Agreements with other airlines
EAS contract term			3 years
Aircraft in schedule service or under contract
Future minimum rental income
Number of aircraft | aircraft			502
Aircraft
Future minimum rental income
Number of aircraft subleased | aircraft	8		8
United
Future minimum rental income
Number of aircraft | aircraft			229
United | United Express Prorate Agreement
Future minimum rental income
Agreement term			120 days
Delta
Future minimum rental income
Number of aircraft | aircraft			142
Delta | Delta Connection Prorate Agreement
Future minimum rental income
Agreement term			30 days
American
Future minimum rental income
Number of aircraft | aircraft			89
American | American Prorate Agreement
Future minimum rental income
Agreement term			180 days
Jet aircraft and spare engines leased to third parties
Future minimum rental income
Property and equipment and related assets	$ 217,700		$ 217,700
CRJ 200 | United | United Express Agreements
Future minimum rental income
Number of aircraft | aircraft			50
CRJ 200 | United | United Express Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft			30
CRJ 550 | United Express Agreements
Future minimum rental income
Number of new aircraft ordered | aircraft	32		32
CRJ 700
Future minimum rental income
Number of seats on aircraft | item			50
CRJ 700 | United | United Express Agreements
Future minimum rental income
Number of aircraft | aircraft			33
CRJ 700 | Delta | Delta Connection Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft			15
CRJ 700 | Delta | Delta Connection Agreements
Future minimum rental income
Number of aircraft | aircraft			5
CRJ 700 | American
Future minimum rental income
Number of aircraft | aircraft			68
CRJ 900 | Delta | Delta Connection Agreements
Future minimum rental income
Number of aircraft | aircraft			35
CRJ 900 | American | American Prorate Agreement
Future minimum rental income
Number of aircraft | aircraft			1
E175
Future minimum rental income
Number of aircraft under purchase agreement | aircraft			74
E175 | United Express Agreements
Future minimum rental income
Number of new aircraft ordered | aircraft	13		13
Number of aircraft scheduled for delivery in 2025 | aircraft	5		5
Number of aircraft scheduled for delivery in 2026 | aircraft	8		8
E175 | Delta Connection Agreements
Future minimum rental income
Number of new aircraft ordered | aircraft	16		16
Number of aircraft delivered in year three | aircraft	10		10
Number of aircraft delivered in year four | aircraft	6		6
E175 | Alaska Capacity Purchase Agreement
Future minimum rental income
Number of new aircraft ordered | aircraft	1		1
E175 | United | United Express Agreements
Future minimum rental income
Number of aircraft | aircraft			116
E175 | Delta | Delta Connection Agreements
Future minimum rental income
Number of aircraft | aircraft			87
E175 | American | American Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft			20
E175 | Alaska | Alaska Capacity Purchase Agreement
Future minimum rental income
Number of aircraft | aircraft			42
Flying agreements
Rental income under operating leases
Total operating revenues	$ 987,511	838,170	$ 1,903,505	1,616,459
Flight operations revenue
Rental income under operating leases
Total operating revenues	682,948	595,127	1,322,101	1,139,287
Capacity purchase agreements fixed aircraft lease revenue
Rental income under operating leases
Total operating revenues	104,220	75,131	215,208	150,290
Capacity purchase agreements variable aircraft lease revenue
Rental income under operating leases
Total operating revenues	54,898	60,841	89,937	118,727
Prorate agreements and SWC revenue
Rental income under operating leases
Total operating revenues	145,445	107,071	276,259	208,155
Airport customer service and other revenue
Rental income under operating leases
Total operating revenues	22,493	6,832	31,880	15,489
Lease, airport services and other.
Rental income under operating leases
Total operating revenues	$ 47,716	$ 28,948	$ 80,177	$ 54,273