OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,681	$ 797
Operating expenses
Operating Expenses, Excluding Fuel	1,536	755
Economic fuel	347	203
Total Operating Expenses	1,883	958
Nonoperating Income (Expense)
Interest income	7	7
Interest expense	(27)	(32)
Interest capitalized	2	3
Other—net	14	10
Nonoperating Income (Expense)	(4)	(12)
Costs and Expenses, Total	1,883	958
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	300	178
Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,681	797
Operating expenses
Operating Expenses, Excluding Fuel	1,461	1,137
Economic fuel	454	225
Total Operating Expenses	1,915	1,362
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(4)	(12)
Income (loss) before income tax	(238)	(577)
Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,400	630
Operating expenses
Operating Expenses, Excluding Fuel	1,194	893
Economic fuel	381	174
Total Operating Expenses	1,575	1,067
Nonoperating Income (Expense)
Nonoperating Income (Expense)	1	(7)
Income (loss) before income tax	(174)	(444)
Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	280	167
Operating expenses
Operating Expenses, Excluding Fuel	262	265
Economic fuel	73	52
Total Operating Expenses	335	317
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0
Income (loss) before income tax	(55)	(150)
Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	94	104
Operating expenses
Operating Expenses, Excluding Fuel	99	88
Economic fuel	0	0
Total Operating Expenses	99	88
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(5)	(5)
Income (loss) before income tax	(10)	11
Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(93)	(104)
Operating expenses
Operating Expenses, Excluding Fuel	(94)	(109)
Economic fuel	0	(1)
Total Operating Expenses	(94)	(110)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0
Income (loss) before income tax	1	6
Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Operating expenses
Operating Expenses, Excluding Fuel	75	(382)
Economic fuel	(107)	(22)
Total Operating Expenses	(32)	(404)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0
Income (loss) before income tax	32	404
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,511	659
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,511	659
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,243	506
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	268	153
Passenger [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Passenger [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Passenger [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Capacity Purchase Agreements [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Capacity Purchase Agreements [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Capacity Purchase Agreements [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Capacity Purchase Agreements [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Capacity Purchase Agreements [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	94	104
Capacity Purchase Agreements [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(94)	(104)
Capacity Purchase Agreements [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	112	94
Mileage plan other revenue [Member] | Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	112	94
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	112	94
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	100	80
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	12	14
Mileage plan other revenue [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Mileage plan other revenue [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Mileage plan other revenue [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	58	44
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	58	44
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	57	44
Cargo and Freight [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Cargo and Freight [Member] | Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Cargo and Freight [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1	0
Cargo and Freight [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0