OPERATING SEGMENT INFORMATION - Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total segment operating revenue	$ 3,137	$ 2,232
Wages and benefits	1,127	804
Aircraft maintenance	220	122
Aircraft rent	62	47
Landing fees and other rentals	242	165
Contracted services	145	97
Selling expenses	100	77
Depreciation and amortization	194	126
Food and beverage service	85	58
Other	261	205
Regional carrier expenses	64	54
Total Operating Expenses	3,334	2,398
Interest income	26	17
Interest expense	(66)	(35)
Other - net	(8)	0
Total Non-operating Expense	(36)	(12)
Loss Before Income Tax	(233)	(178)
Reconciliation to Consolidated Loss Before Income Tax:
Special items - operating	91	34
Total assets	19,818		$ 19,768
Capital expenditures	261	102
Passenger revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	2,808	2,004
Mileage Plan Revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	523	412
Cargo and other revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	122	64
Passenger | Passenger revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	2,808	2,004
Passenger | Mileage Plan Revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	316	248
Mileage plan other revenue | Mileage Plan Revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	207	164
Cargo and Freight | Cargo and other revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	122	64
Operating Segments
Segment Reporting Information [Line Items]
Total segment operating revenue	3,135	2,230
Wages and benefits	998	683
Variable incentive pay	56	39
Economic fuel	684	578
Aircraft maintenance	199	107
Aircraft rent	36	20
Landing fees and other rentals	208	137
Contracted services	170	120
Selling expenses	92	67
Depreciation and amortization	179	112
Food and beverage service	79	52
Other	231	177
Regional carrier expenses	333	299
Total Operating Expenses	3,265	2,391
Interest income	46	18
Interest expense	(78)	(25)
Other - net	9	4
Total Non-operating Expense	(23)	(3)
Loss Before Income Tax	(153)	(164)
Operating Segments | Alaska Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	1,974	1,840
Wages and benefits	721	683
Variable incentive pay	43	39
Economic fuel	419	485
Aircraft maintenance	124	107
Aircraft rent	21	20
Landing fees and other rentals	154	137
Contracted services	134	120
Selling expenses	62	67
Depreciation and amortization	121	112
Food and beverage service	55	52
Other	173	177
Regional carrier expenses	0	0
Total Operating Expenses	2,027	1,999
Interest income	43	18
Interest expense	(52)	(25)
Other - net	7	4
Total Non-operating Expense	(2)	(3)
Loss Before Income Tax	(55)	(162)
Reconciliation to Consolidated Loss Before Income Tax:
Total assets	24,404		24,664
Capital expenditures	92	52
Operating Segments | Hawaiian Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	747	0
Wages and benefits	277	0
Variable incentive pay	13	0
Economic fuel	174	0
Aircraft maintenance	75	0
Aircraft rent	15	0
Landing fees and other rentals	54	0
Contracted services	36	0
Selling expenses	30	0
Depreciation and amortization	58	0
Food and beverage service	24	0
Other	58	0
Regional carrier expenses	0	0
Total Operating Expenses	814	0
Interest income	3	0
Interest expense	(26)	0
Other - net	2	0
Total Non-operating Expense	(21)	0
Loss Before Income Tax	(88)	0
Reconciliation to Consolidated Loss Before Income Tax:
Total assets	4,549		4,423
Capital expenditures	144	0
Operating Segments | Regional
Segment Reporting Information [Line Items]
Total segment operating revenue	414	390
Wages and benefits	0	0
Variable incentive pay	0	0
Economic fuel	91	93
Aircraft maintenance	0	0
Aircraft rent	0	0
Landing fees and other rentals	0	0
Contracted services	0	0
Selling expenses	0	0
Depreciation and amortization	0	0
Food and beverage service	0	0
Other	0	0
Regional carrier expenses	333	299
Total Operating Expenses	424	392
Interest income	0	0
Interest expense	0	0
Other - net	0	0
Total Non-operating Expense	0	0
Loss Before Income Tax	(10)	(2)
Operating Segments | Passenger | Passenger revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	2,808	2,004
Operating Segments | Passenger | Passenger revenue | Alaska Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	1,757	1,629
Operating Segments | Passenger | Passenger revenue | Hawaiian Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	653	0
Operating Segments | Passenger | Passenger revenue | Regional
Segment Reporting Information [Line Items]
Total segment operating revenue	398	375
Operating Segments | Mileage plan other revenue | Mileage Plan Revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	207	164
Operating Segments | Mileage plan other revenue | Mileage Plan Revenue | Alaska Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	152	149
Operating Segments | Mileage plan other revenue | Mileage Plan Revenue | Hawaiian Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	39	0
Operating Segments | Mileage plan other revenue | Mileage Plan Revenue | Regional
Segment Reporting Information [Line Items]
Total segment operating revenue	16	15
Operating Segments | Cargo and Freight | Cargo and other revenue
Segment Reporting Information [Line Items]
Total segment operating revenue	120	62
Operating Segments | Cargo and Freight | Cargo and other revenue | Alaska Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	65	62
Operating Segments | Cargo and Freight | Cargo and other revenue | Hawaiian Airlines
Segment Reporting Information [Line Items]
Total segment operating revenue	55	0
Operating Segments | Cargo and Freight | Cargo and other revenue | Regional
Segment Reporting Information [Line Items]
Total segment operating revenue	0	0
Corporate And Eliminations
Segment Reporting Information [Line Items]
Total segment operating revenue	2	2
Loss Before Income Tax	13	7
Reconciliation to Consolidated Loss Before Income Tax:
Total assets	(9,135)		$ (9,319)
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Reconciliation to Consolidated Loss Before Income Tax:
Aircraft fuel mark-to-market adjustment	3	13
Losses on foreign debt	(5)
Special items - operating	(91)	(34)
Segment Reporting, Reconciling Item, Corporate Nonsegment
Reconciliation to Consolidated Loss Before Income Tax:
Capital expenditures	25	50
Segment Reporting, Reconciling Item, Corporate Nonsegment | Embraer E175 aircraft
Reconciliation to Consolidated Loss Before Income Tax:
Capital expenditures	$ 23	$ 45