OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,897	$ 2,838	$ 5,129	$ 5,034
Operating expenses
Operating Expenses, Excluding Fuel	1,960	1,928	3,793	3,645
Economic fuel	615	573	1,180	1,238
Total Operating Expenses	2,575	2,501	4,973	4,883
Nonoperating Income (Expense)
Interest income	24	22	41	39
Interest expense	(36)	(28)	(71)	(56)
Interest capitalized	6	7	12	14
Other—net	0	(7)	0	(16)
Nonoperating Income (Expense)	(6)	(12)	(18)	(25)
Costs and Expenses, Total	$ 2,575	$ 2,501	$ 4,973	$ 4,883
Pretax Margin, Adjusted	15.80%	18.30%	5.80%	8.00%
Pretax Margin, GAAP	10.90%	11.50%	2.70%	2.50%
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 464	$ 438	$ 876	$ 824
Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,897	2,838	5,129	5,034
Operating expenses
Operating Expenses, Excluding Fuel	1,814	1,742	3,613	3,395
Economic fuel	620	572	1,198	1,217
Total Operating Expenses	2,434	2,314	4,811	4,612
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(6)	(6)	(18)	(19)
Income (loss) before income tax	457	518	300	403
Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,417	2,434	4,257	4,307
Operating expenses
Operating Expenses, Excluding Fuel	1,516	1,468	3,030	2,858
Economic fuel	520	490	1,005	1,051
Total Operating Expenses	2,036	1,958	4,035	3,909
Nonoperating Income (Expense)
Nonoperating Income (Expense)	6	3	3	(3)
Income (loss) before income tax	387	479	225	395
Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	477	401	867	723
Operating expenses
Operating Expenses, Excluding Fuel	322	279	621	535
Economic fuel	100	81	193	166
Total Operating Expenses	422	360	814	701
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	55	41	53	22
Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	112	92	216	170
Operating expenses
Operating Expenses, Excluding Fuel	92	87	180	171
Economic fuel	0	0	0	0
Total Operating Expenses	92	87	180	171
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(12)	(10)	(23)	(18)
Income (loss) before income tax	8	(5)	13	(19)
Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(109)	(89)	(211)	(166)
Operating expenses
Operating Expenses, Excluding Fuel	(116)	(92)	(218)	(169)
Economic fuel	0	1	0	0
Total Operating Expenses	(116)	(91)	(218)	(169)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	1	2	2
Income (loss) before income tax	7	3	9	5
Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	146	186	180	250
Economic fuel	(5)	1	(18)	21
Total Operating Expenses	141	187	162	271
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	(6)	0	(6)
Income (loss) before income tax	(141)	(193)	(162)	(277)
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,651	2,598	4,655	4,582
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,651	2,598	4,655	4,582
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,188	2,209	3,817	3,882
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	463	389	838	700
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	112	92	216	170
Capacity Purchase Agreements [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(112)	(92)	(216)	(170)
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	174	170	338	324
Mileage plan other revenue [Member] | Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	174	170	338	324
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	174	170	338	324
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	160	158	309	301
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	14	12	29	23
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	72	70	136	128
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	72	70	136	128
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	69	67	131	124
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	3	3	5	4
Cargo and Freight [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0	$ 0	$ 0