Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Carrying Amount and Estimated Fair Value, Long-term Debt

The carrying amounts and estimated fair values of the Company's long-term debt at June 30, 2023 and December 31, 2022 were as follows:

	June 30, 2023				December 31, 2022				Fair Value Level Hierarchy
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
8.00% senior secured notes	$	1,110.0	$	1,105.4	$	1,110.0	$	1,085.0	Level 3
Fixed-rate term loans	1,028.3		959.8		1,094.7		1,003.9		Level 3
Unsecured term loans	136.3		120.9		136.3		116.0		Level 3
2015-1 EETC Class A	267.6		239.5		278.6		247.5		Level 2
2015-1 EETC Class B	44.0		42.5		48.0		45.6		Level 2
2015-1 EETC Class C	—		—		63.8		63.1		Level 2
2017-1 EETC Class AA	179.2		156.8		186.3		161.6		Level 2
2017-1 EETC Class A	59.7		50.8		62.1		52.3		Level 2
2017-1 EETC Class B	49.9		44.0		51.7		44.9		Level 2
2017-1 EETC Class C	—		—		85.5		85.1		Level 2
4.75% convertible notes due 2025	25.1		42.7		25.4		44.9		Level 2
1.00% convertible notes due 2026	500.0		404.8		500.0		405.1		Level 2
Total long-term debt	$	3,400.1	$	3,167.2	$	3,642.4	$	3,355.0

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:

	Fair Value Measurements as of June 30, 2023
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	1,110.7	$	1,110.7	$	—	$	—
Restricted cash	119.4		119.4		—		—
Short-term investment securities	109.5		109.5		—		—
Assets held for sale	1.9		—		—		1.9
Total assets	$	1,341.5	$	1,339.6	$	—	$	1.9
Derivative liability	$	16.7	$	—	$	16.7	$	—
Total liabilities	$	16.7	$	—	$	16.7	$	—

	Fair Value Measurements as of December 31, 2022
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	1,346.4	$	1,346.4	$	—	$	—
Restricted cash	119.4		119.4		—		—
Short-term investment securities	107.1		107.1		—		—
Assets held for sale	2.5		—		—		2.5
Total assets	$	1,575.4	$	1,572.9	$	—	$	2.5
Derivative liability	$	29.2	$	—	29.2		$	—
Total liabilities	$	29.2	$	—	$	29.2	$	—