OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,658	$ 1,527	$ 4,339	$ 2,324
Operating expenses
Operating Expenses, Excluding Fuel	1,695	704	3,231	1,459
Economic fuel	776	274	1,123	477
Total Operating Expenses	2,471	978	4,354	1,936
Nonoperating Income (Expense)
Interest income	11	6	18	13
Interest expense	(26)	(39)	(53)	(71)
Interest capitalized	3	3	5	6
Other—net	10	9	24	19
Nonoperating Income (Expense)	(2)	(21)	(6)	(33)
Costs and Expenses, Total	$ 2,471	$ 978	$ 4,354	$ 1,936
Pretax Margin, Adjusted	14.00%	(3.10%)	3.10%	(26.90%)
Pretax Margin, GAAP	7.00%	34.60%	(0.50%)	15.30%
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 422	$ 272	$ 722	$ 450
Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,658	1,527	4,339	2,324
Operating expenses
Operating Expenses, Excluding Fuel	1,549	1,234	3,010	2,371
Economic fuel	736	320	1,190	545
Total Operating Expenses	2,285	1,554	4,200	2,916
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(2)	(21)	(6)	(33)
Income (loss) before income tax	371	(48)	133	(625)
Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,251	1,229	3,651	1,859
Operating expenses
Operating Expenses, Excluding Fuel	1,262	984	2,456	1,877
Economic fuel	617	253	998	427
Total Operating Expenses	1,879	1,237	3,454	2,304
Nonoperating Income (Expense)
Nonoperating Income (Expense)	3	(16)	4	(23)
Income (loss) before income tax	375	(24)	201	(468)
Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	406	296	686	463
Operating expenses
Operating Expenses, Excluding Fuel	289	286	551	551
Economic fuel	119	66	192	118
Total Operating Expenses	408	352	743	669
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	(2)	(56)	(57)	(206)
Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	101	111	195	215
Operating expenses
Operating Expenses, Excluding Fuel	98	91	197	179
Economic fuel	0	0	0	0
Total Operating Expenses	98	91	197	179
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(5)	(5)	(10)	(10)
Income (loss) before income tax	(2)	15	(12)	26
Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(100)	(109)	(193)	(213)
Operating expenses
Operating Expenses, Excluding Fuel	(100)	(127)	(194)	(236)
Economic fuel	0	1	0	0
Total Operating Expenses	(100)	(126)	(194)	(236)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	0	17	1	23
Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	146	(530)	221	(912)
Economic fuel	40	(46)	(67)	(68)
Total Operating Expenses	186	(576)	154	(980)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	(186)	576	(154)	980
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,418	1,352	3,929	2,011
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,418	1,352	3,929	2,011
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,028	1,072	3,271	1,578
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	390	280	658	433
Passenger [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Passenger [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Passenger [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Capacity Purchase Agreements [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Capacity Purchase Agreements [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Capacity Purchase Agreements [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Capacity Purchase Agreements [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Capacity Purchase Agreements [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	101	111	195	215
Capacity Purchase Agreements [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(101)	(111)	(195)	(215)
Capacity Purchase Agreements [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	175	118	287	212
Mileage plan other revenue [Member] | Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	175	118	287	212
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	175	118	287	212
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	159	102	259	182
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	16	16	28	30
Mileage plan other revenue [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Mileage plan other revenue [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Mileage plan other revenue [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	65	57	123	101
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	65	57	123	101
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	64	55	121	99
Cargo and Freight [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Cargo and Freight [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Cargo and Freight [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1	2	2	2
Cargo and Freight [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0	$ 0	$ 0