OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,838	$ 2,658	$ 5,034	$ 4,339
Operating expenses
Operating Expenses, Excluding Fuel	1,928	1,695	3,645	3,231
Economic fuel	573	776	1,238	1,123
Total Operating Expenses	2,501	2,471	4,883	4,354
Nonoperating Income (Expense)
Interest income	22	11	39	18
Interest expense	(28)	(26)	(56)	(53)
Interest capitalized	7	3	14	5
Other—net	(7)	10	(16)	24
Nonoperating Income (Expense)	(12)	(2)	(25)	(6)
Costs and Expenses, Total	$ 2,501	$ 2,471	$ 4,883	$ 4,354
Pretax Margin, Adjusted	18.30%	14.00%	8.00%	3.10%
Pretax Margin, GAAP	11.50%	7.00%	2.50%	(0.50%)
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 438	$ 422	$ 824	$ 722
Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,838	2,658	5,034	4,339
Operating expenses
Operating Expenses, Excluding Fuel	1,742	1,549	3,395	3,010
Economic fuel	572	736	1,217	1,190
Total Operating Expenses	2,314	2,285	4,612	4,200
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(6)	(2)	(19)	(6)
Income (loss) before income tax	518	371	403	133
Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,453	2,251	4,343	3,651
Operating expenses
Operating Expenses, Excluding Fuel	1,468	1,262	2,858	2,456
Economic fuel	490	617	1,051	998
Total Operating Expenses	1,958	1,879	3,909	3,454
Nonoperating Income (Expense)
Nonoperating Income (Expense)	3	3	(3)	4
Income (loss) before income tax	498	375	431	201
Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	382	406	687	686
Operating expenses
Operating Expenses, Excluding Fuel	279	289	535	551
Economic fuel	81	119	166	192
Total Operating Expenses	360	408	701	743
Nonoperating Income (Expense)
Nonoperating Income (Expense)	0	0	0	0
Income (loss) before income tax	22	(2)	(14)	(57)
Horizon [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	92	101	170	195
Operating expenses
Operating Expenses, Excluding Fuel	87	98	171	197
Economic fuel	0	0	0	0
Total Operating Expenses	87	98	171	197
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(10)	(5)	(18)	(10)
Income (loss) before income tax	(5)	(2)	(19)	(12)
Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(89)	(100)	(166)	(193)
Operating expenses
Operating Expenses, Excluding Fuel	(92)	(100)	(169)	(194)
Economic fuel	1	0	0	0
Total Operating Expenses	(91)	(100)	(169)	(194)
Nonoperating Income (Expense)
Nonoperating Income (Expense)	1	0	2	0
Income (loss) before income tax	3	0	5	1
Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	186	146	250	221
Economic fuel	1	40	21	(67)
Total Operating Expenses	187	186	271	154
Nonoperating Income (Expense)
Nonoperating Income (Expense)	(6)	0	(6)	0
Income (loss) before income tax	(193)	(186)	(277)	(154)
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,598	2,418	4,582	3,929
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,598	2,418	4,582	3,929
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,228	2,028	3,918	3,271
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	370	390	664	658
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	92	101	170	195
Capacity Purchase Agreements [Member] | Consolidating and Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(92)	(101)	(170)	(195)
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	170	175	324	287
Mileage plan other revenue [Member] | Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	170	175	324	287
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	170	175	324	287
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	158	159	301	259
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	12	16	23	28
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	70	65	128	123
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	70	65	128	123
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	67	64	124	121
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	1	4	2
Cargo and Freight [Member] | Special Charges [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0	$ 0	$ 0