Fresh Start Accounting - Narrative (Details) $ in Thousands			3 Months Ended
	Mar. 13, 2025 USD ($) debtInstrument shares	Mar. 12, 2025 USD ($) shares	Mar. 31, 2025 USD ($) airportTake-offAndLandingRight aircraft	Mar. 31, 2024 USD ($)	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	$ 8,910,118			$ 9,595,178
Reorganization value	8,720,000	$ 9,819,000
Selected enterprise value within bankruptcy court range	$ 6,450,000
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	8
Number of aircraft to be purchased | aircraft			22
Repayments of long-term debt			$ 31,800	$ 46,800
Warrant outstanding (in shares) | shares	24,255,256	24,255,256
Intangible assets	$ 83,482		83,482			550
Deferred income taxes	$ 69,408		$ 69,305			$ 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)
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
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") | airportTake-offAndLandingRight			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%