Fresh Start Accounting- 2024 Bankruptcy - Narrative (Details) $ in Thousands			2 Months Ended	3 Months Ended	7 Months Ended
	Mar. 13, 2025 USD ($) debtInstrument aircraft shares	Mar. 12, 2025 USD ($)	Mar. 12, 2025 USD ($)	Sep. 30, 2025 USD ($) right aircraft	Sep. 30, 2025 USD ($) right aircraft	Mar. 18, 2025	Dec. 31, 2024 USD ($)
Reorganization, Chapter 11 [Line Items]
Reorganization, percent of successor common shares received by predecessor shareholders less than	50.00%
Assets	$ 8,719,994	$ 8,720,000	$ 8,720,000	$ 8,795,044	$ 8,795,044		$ 9,595,178
Reorganization value	8,720,000	9,819,000	9,819,000
Selected enterprise value within bankruptcy court range	$ 6,450,000
Number of aircraft transferred from held-for-sale | aircraft				20	20
Number of Exit Secured Notes | debtInstrument	35
Number of publicly-traded Enhances Equipment Trust Certificates ("EETCs") | debtInstrument	4
Number of fixed aircraft loans | debtInstrument	22
Number of Payroll Support Program Agreements | debtInstrument	3
Number of aircraft to be purchased | aircraft	22
Repayments of long-term debt			25,500	$ 21,400	$ 63,500
Warrant outstanding (in shares) | shares	24,255,256
Intangible assets	$ 83,482			83,482	83,482		550
Deferred income taxes	$ 69,408			$ 65,988	$ 65,988		$ 51,927
Warrants, Tranche 1
Reorganization, Chapter 11 [Line Items]
Warrant outstanding (in shares) | shares	3,617,385
Warrants, Tranche 2
Reorganization, Chapter 11 [Line Items]
Warrant outstanding (in shares) | shares	20,637,871
Private Placement
Reorganization, Chapter 11 [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares	16,067,305
Warrant outstanding (in shares) | shares	13,380,504
Reorganization Items
Reorganization, Chapter 11 [Line Items]
Assets		(286,711)	(286,711)
Payment of professional fees at Emergence		8,191
Debtor reorganization items, success fees		2,600
Repayments of long-term debt		309,000
Capitalized heavy maintenance costs, write-off		120,900
Impact of deferred gain on sale leaseback write off		24,500
Deferred income taxes		$ 16,900	$ 16,900
Reorganization Items | Air Carrier Slots
Reorganization, Chapter 11 [Line Items]
Intangible assets	$ 83,500
Exit secured notes | Secured Debt
Reorganization, Chapter 11 [Line Items]
Principal amount	$ 840,000
Stated interest rate percentage						92.50%
LaGuardia Airport | Valuation, Market Approach Or Income Approach
Reorganization, Chapter 11 [Line Items]
Number of airport take-off and landing sights ("Slots") | right				22	22
G.A. Telesis
Reorganization, Chapter 11 [Line Items]
Number of aircraft to be sold | aircraft	21
Minimum
Reorganization, Chapter 11 [Line Items]
Selected enterprise value within bankruptcy court range	$ 6,100,000
Debt instrument, fair value, aircraft loan (as a percent)	95.61%
Minimum | Exit secured notes | Secured Debt
Reorganization, Chapter 11 [Line Items]
Stated interest rate percentage	11.00%
Minimum | Enhanced Equipment Trust Certificate | Secured Debt
Reorganization, Chapter 11 [Line Items]
Stated interest rate percentage	87.32%
Maximum
Reorganization, Chapter 11 [Line Items]
Selected enterprise value within bankruptcy court range	$ 6,800,000
Debt instrument, fair value, aircraft loan (as a percent)	99.84%
Maximum | Exit secured notes | Secured Debt
Reorganization, Chapter 11 [Line Items]
Stated interest rate percentage	12.00%
Maximum | Enhanced Equipment Trust Certificate | Secured Debt
Reorganization, Chapter 11 [Line Items]
Stated interest rate percentage	92.85%