OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,839	$ 2,828	$ 7,873	$ 7,167
Operating expenses
Operating Expenses, Excluding Fuel	1,934	1,889	5,579	5,120
Economic fuel	694	877	1,932	2,000
Total Operating Expenses	2,628	2,766	7,511	7,120
Nonoperating Income (Expense)
Interest income	23	17	62	35
Interest expense	(34)	(31)	(90)	(84)
Interest capitalized	7	3	21	8
Other—net	(6)	14	(22)	38
Nonoperating Income (Expense)	(18)	3	(43)	(3)
Costs and Expenses, Total	$ 2,628	$ 2,766	$ 7,511	$ 7,120
Pretax Margin, Adjusted	11.40%	15.60%	9.20%	8.00%
Pretax Margin, GAAP	6.80%	2.30%	4.10%	0.60%
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 416	$ 382	$ 1,240	$ 1,104
Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,839	2,828	7,873	7,167
Operating expenses
Operating Expenses, Excluding Fuel	1,778	1,644	5,173	4,654
Economic fuel	729	746	1,946	1,936
Total Operating Expenses	2,507	2,390	7,119	6,590
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(10)	3	(29)	(3)
Income (loss) before income tax	322	441	725	574
Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,431	2,415	6,774	6,066
Operating expenses
Operating Expenses, Excluding Fuel	1,484	1,352	4,342	3,808
Economic fuel	621	625	1,672	1,623
Total Operating Expenses	2,105	1,977	6,014	5,431
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	8	(3)	12
Income (loss) before income tax	326	446	757	647
Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	406	411	1,093	1,097
Operating expenses
Operating Expenses, Excluding Fuel	297	292	832	843
Economic fuel	108	121	274	313
Total Operating Expenses	405	413	1,106	1,156
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	1	(2)	(13)	(59)
Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	104	93	274	288
Operating expenses
Operating Expenses, Excluding Fuel	89	94	260	291
Economic fuel	0	0	0	0
Total Operating Expenses	89	94	260	291
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(11)	(5)	(29)	(15)
Income (loss) before income tax	4	(6)	(15)	(18)
Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(102)	(91)	(268)	(284)
Operating expenses
Operating Expenses, Excluding Fuel	(92)	(94)	(261)	(288)
Economic fuel	0	0	0	0
Total Operating Expenses	(92)	(94)	(261)	(288)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	1	0	3	0
Income (loss) before income tax	(9)	3	(4)	4
Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	156	245	406	466
Economic fuel	(35)	131	(14)	64
Total Operating Expenses	121	376	392	530
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(8)	0	(14)	0
Income (loss) before income tax	(129)	(376)	(406)	(530)
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,618	2,615	7,200	6,544
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,618	2,615	7,200	6,544
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,225	2,217	6,143	5,488
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	393	398	1,057	1,056
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	104	93	274	288
Capacity Purchase Agreements [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(104)	(93)	(274)	(288)
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	159	146	483	433
Mileage plan other revenue [Member] | Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	159	146	483	433
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	159	146	483	433
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	146	133	447	392
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	13	13	36	41
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	62	67	190	190
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	62	67	190	190
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	60	65	184	186
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	2	2	6	4
Cargo and Freight [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0	$ 0	$ 0