Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2025

Fair Value Disclosures [Abstract]

Schedule of Carrying Amount and Estimated Fair Value, Long-term Debt

The carrying amounts and estimated fair values of the Company's long-term debt at September 30, 2025 and December 31, 2024 were as follows (in millions):

	Successor				Predecessor
	September 30, 2025				December 31, 2024				Fair Value Level Hierarchy
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
2024 Bankruptcy DIP term loans	$	—	$	—	$	309.0	$	309.0	Level 3
Fixed-rate term loans (1)	294.6		326.5		972.2		970.7		Level 3
Unsecured term loans (1)	—		—		136.3		130.4		Level 3
2015-1 EETC Class A	223.6		209.1		234.6		215.8		Level 2
2017-1 EETC Class AA	152.3		139.4		160.3		140.4		Level 2
2017-1 EETC Class A	45.5		40.3		53.4		45.8		Level 2
2017-1 EETC Class B	—		—		44.7		40.5		Level 2
2025-1 EETC Class B	215.0		204.3		—		—		Level 2
Revolving credit facility (1)	—		—		300.0		300.0		Level 3
Total long-term debt	$	931.0	$	919.6	$	2,210.5	$	2,152.6

(1) As of September 30, 2025, the Company's 18 failed sale leasebacks, included within fixed-rate term loans, unsecured term-loans, Exit Secured Notes and its Revolving Credit Facility are classified as liabilities subject to compromise on the Company's condensed consolidated balance sheets. Refer to Note 3, 2025 Chapter 11 Bankruptcy Proceedings, for additional information.

Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis

Assets and liabilities measured at gross fair value on a recurring basis are summarized below (in millions):

	Successor Fair Value Measurements as of September 30, 2025
	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	250.5	$	250.5	$	—	$	—
Restricted cash	396.1		396.1		—		—
Short-term investment securities	—		—		—		—
Assets held for sale	3.1		—		—		3.1
Total assets	$	649.7	$	646.6	$	—	$	3.1
Total liabilities	$	—	$	—	$	—	$	—

	Predecessor Fair Value Measurements as of December 31, 2024
	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	902.1	$	902.1	$	—	$	—
Restricted cash	168.4		168.4		—		—
Short-term investment securities	118.3		118.3		—		—
Assets held for sale	463.0		—		—		463.0
Total assets	$	1,651.8	$	1,188.8	$	—	$	463.0
Total liabilities	$	—	$	—	$	—	$	—