Consolidated Statements of Cash Flows - USD ($) $ in Thousands		2 Months Ended	10 Months Ended	12 Months Ended
		Mar. 12, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating activities:
Net income (loss)		$ 72,216	$ (2,832,669)	$ (1,229,495)	$ (447,464)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operations:
Losses reclassified from other comprehensive income		34	0	103	314
Share-based compensation		1,233	6,611	7,210	11,963
Allowance for doubtful accounts (recoveries)		0	(831)	822	159
Amortization of debt issuance costs		1,003	2,608	13,100	15,454
Amortization of debt fair value adjustment (fresh start accounting)		0	23,770	0	0
Depreciation and amortization		54,853	190,244	325,273	320,872
Accretion of convertible debt and 8.00% senior secured notes		0	0	3,821	4,210
Amortization of debt discount		0	2,595	10,156	8,145
Deferred income tax expense (benefit)		17,481	(9,970)	(58,215)	(119,239)
Loss (gain) on disposal of assets		11,655	(109,096)	273,871	33,966
Reorganization items		(421,464)	2,272,243	85,554	0
Changes in operating assets and liabilities:
Accounts receivable, net		(22,726)	76,093	26,797	(8,351)
Deposits and other assets		13,597	(195,173)	(76,744)	4,215
Deferred heavy maintenance		(26,736)	(30,071)	(86,412)	(202,926)
Income tax receivable		0	0	(96)	36,261
Accounts payable		14,240	105,534	(40,124)	(34,051)
Air traffic liability		81,855	(180,472)	53,062	(45,867)
Other liabilities		(20,165)	(27,117)	(63,688)	176,440
Other		(767)	(898)	(3,082)	(762)
Net cash provided by (used in) operating activities		(223,691)	(706,599)	(758,087)	(246,661)
Investing activities:
Purchase of available-for-sale investment securities		(25,072)	(27,996)	(161,745)	(127,627)
Proceeds from the maturity and sale of available-for-sale investment securities		24,750	148,186	160,350	125,570
Proceeds from sale of property and equipment		0	271,261	232,564	230,788
Pre-delivery deposit and other payments on flight equipment		(1,411)	(4,234)	(6,471)	(86,245)
Pre-delivery deposit refunds on flight equipment		26,434	24,617	362,765	109,401
Capitalized interest		(1,331)	(813)	(14,475)	(21,860)
Assets under construction for others		2,875	9,546	1,568	(10,972)
Purchase of property and equipment		(7,204)	(35,864)	(110,955)	(255,563)
Net cash provided by (used in) investing activities		19,041	384,703	463,601	(36,508)
Financing activities:
Proceeds from issuance of long-term debt		0	490,000	423,500	457,950
Proceeds from issuance of common stock and warrants		350,000	0	0	0
Proceeds from DIP financing		0	339,500	300,000	0
Payments on debt obligations		(634,506)	(135,988)	(185,446)	(337,475)
Payments for the early extinguishment of debt		0	(61,040)	(140,679)	(323,251)
Payments on finance lease obligations		(37)	(183)	(312)	(496)
Reimbursement for assets under construction for others		(2,573)	(9,569)	(1,568)	10,974
Repurchase of common stock		0	0	(650)	(2,637)
Debt and equity financing costs		(13,456)	(1,738)	(14,523)	(3,027)
Net cash provided by (used in) financing activities		(300,572)	620,982	380,322	(197,962)
Net increase (decrease) in cash, cash equivalents, and restricted cash		(505,222)	299,086	85,836	(481,131)
Cash, cash equivalents, and restricted cash at beginning of period	[1]	1,070,447	565,225	984,611	1,465,742
Cash, cash equivalents, and restricted cash at end of period	[1]	565,225	864,311	1,070,447	984,611
Cash payments for:
Interest, net of capitalized interest		64,790	90,637	176,187	138,380
Income taxes paid (received), net		152	1,829	3,548	(32,854)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases		96,575	377,314	532,499	400,999
Financing cash flows for finance leases		5	18	33	30
Non-cash transactions:
Capital expenditures funded by finance lease borrowings		0	0	274	145
Capital expenditures funded by operating lease borrowings		$ 98,385	$ 314,612	$ 1,312,237	$ 1,076,456

[1] The sum of cash and cash equivalents and restricted cash on the consolidated balance sheets equals cash, cash equivalents and restricted cash in the consolidated statements of cash flows.