CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2026	Mar. 31, 2025
NET CASH PROVIDED BY OPERATING ACTIVITIES		$ 57.8	$ 53.8
INVESTING ACTIVITIES:
Purchase of property and equipment	[1]	(93.1)	(39.3)
Proceeds from insurance, sale of property, and other equipment		1.8	0.3
Pre-delivery deposits paid	[1]	(2.0)	(9.2)
Purchases of marketable securities and investments		(38.7)	(38.4)
Proceeds from the sale of marketable securities		40.0	45.0
NET CASH USED IN INVESTING ACTIVITIES		(92.0)	(41.6)
FINANCING ACTIVITIES:
Proceeds from issuance of debt		64.4	22.4
Payments on debt and finance lease obligations		(48.8)	(57.4)
Payments for warrant redemption		(5.3)	0.0
Other, net		(0.3)	(0.9)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES		10.0	(35.9)
NET CHANGES IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		(24.2)	(23.7)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH—Beginning of period		157.7	131.9
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH—End of period		133.5	108.2
CASH PAID FOR:
Interest, net of capitalized amounts		16.6	14.1
Income taxes, net of refunds		4.3	3.4
Amounts included in the measurement of operating lease liabilities		6.1	5.1
SUPPLEMENTAL DISCLOSURE OF NON-CASH TRANSACTIONS:
Property and equipment acquired, but not paid		11.7	6.6
Right-of-use assets acquired or modified under operating leases		0.4	(0.5)
Nonrelated Party
SUPPLEMENTAL DISCLOSURE OF NON-CASH TRANSACTIONS:
Parts credits received from aircraft and engine manufacturers		2.4	0.5
Related Party
SUPPLEMENTAL DISCLOSURE OF NON-CASH TRANSACTIONS:
Parts credits received from aircraft and engine manufacturers		$ 0.2	$ 0.2

[1] The Company made net aircraft, pre-delivery deposit payments, and inventory and rotable spare part purchases from its original equipment manufacturer, a related party, of $71.7 million and $32.1 million during the three months ended March 31, 2026 and 2025, respectively.