OPERATING SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) airline	Sep. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Airlines | airline			2
Number of Operating Segments | airline			3
Operating revenues
Passenger, Mainline	$ 1,073	$ 1,057	$ 3,036	$ 2,977
Passenger, Regional	249	240	682	638
Total passenger revenue	1,322	1,297	3,718	3,615
CPA revenues	0	0	0	0
Freight and mail	31	30	82	83
Other - net revenue	213	188	607	523
Total Operating Revenues	1,566	1,515	4,407	4,221
Operating expenses
Operating expenses, excluding fuel	941	837	2,706	2,437
Economic fuel	225	245	593	741
Total Operating Expenses	1,166	1,082	3,299	3,178
Nonoperating Income (Expense)
Interest income	7	5	20	16
Interest expense	(11)	(10)	(33)	(32)
Other	6	9	19	26
Nonoperating Income (Expense) Total	2	4	6	10
Income before income tax	402	437	$ 1,114	1,053
Air Group Adjusted [Member]
Segment Reporting Information [Line Items]
Number of Airlines | airline			2
Operating revenues
Passenger, Mainline	1,073	1,057	$ 3,036	2,977
Passenger, Regional	249	240	682	638
Total passenger revenue	1,322	1,297	3,718	3,615
CPA revenues	0	0	0	0
Freight and mail	31	30	82	83
Other - net revenue	213	188	607	523
Total Operating Revenues	1,566	1,515	4,407	4,221
Operating expenses
Operating expenses, excluding fuel	919	837	2,670	2,437
Economic fuel	222	240	602	742
Total Operating Expenses	1,141	1,077	3,272	3,179
Nonoperating Income (Expense)
Interest income	7	5	20	16
Interest expense	(11)	(10)	(33)	(32)
Other	6	9	19	26
Nonoperating Income (Expense) Total	2	4	6	10
Income before income tax	427	442	1,141	1,052
Alaska Mainline [Member]
Operating revenues
Passenger, Mainline	1,073	1,057	3,036	2,977
Passenger, Regional	0	0	0	0
Total passenger revenue	1,073	1,057	3,036	2,977
CPA revenues	0	0	0	0
Freight and mail	30	29	79	79
Other - net revenue	190	167	546	465
Total Operating Revenues	1,293	1,253	3,661	3,521
Operating expenses
Operating expenses, excluding fuel	727	667	2,107	1,951
Economic fuel	188	205	512	641
Total Operating Expenses	915	872	2,619	2,592
Nonoperating Income (Expense)
Interest income	7	5	19	15
Interest expense	(7)	(7)	(23)	(21)
Other	5	7	15	21
Nonoperating Income (Expense) Total	5	5	11	15
Income before income tax	383	386	1,053	944
Alaska Regional [Member]
Operating revenues
Passenger, Mainline	0	0	0	0
Passenger, Regional	249	240	682	638
Total passenger revenue	249	240	682	638
CPA revenues	0	0	0	0
Freight and mail	1	1	3	4
Other - net revenue	21	20	57	55
Total Operating Revenues	271	261	742	697
Operating expenses
Operating expenses, excluding fuel	202	181	580	514
Economic fuel	34	35	90	101
Total Operating Expenses	236	216	670	615
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Other	0	0	0	0
Nonoperating Income (Expense) Total	0	0	0	0
Income before income tax	$ 35	45	$ 72	82
Horizon [Member]
Segment Reporting Information [Line Items]
Capacity purchase arrangements	100.00%		100.00%
Operating revenues
Passenger, Mainline	$ 0	0	$ 0	0
Passenger, Regional	0	0	0	0
Total passenger revenue	0	0	0	0
CPA revenues	109	105	322	303
Freight and mail	0	0	0	0
Other - net revenue	1	1	3	3
Total Operating Revenues	110	106	325	306
Operating expenses
Operating expenses, excluding fuel	99	93	305	274
Economic fuel	0	0	0	0
Total Operating Expenses	99	93	305	274
Nonoperating Income (Expense)
Interest income	0	0	1	0
Interest expense	(2)	(3)	(7)	(8)
Other	0	0	0	0
Nonoperating Income (Expense) Total	(2)	(3)	(6)	(8)
Income before income tax	9	10	14	24
Intersegment Elimination [Member]
Operating revenues
Passenger, Mainline	0	0	0	0
Passenger, Regional	0	0	0	0
Total passenger revenue	0	0	0	0
CPA revenues	(109)	(105)	(322)	(303)
Freight and mail	0	0	0	0
Other - net revenue	1	0	1	0
Total Operating Revenues	(108)	(105)	(321)	(303)
Operating expenses
Operating expenses, excluding fuel	(109)	(104)	(322)	(302)
Economic fuel	0	0	0	0
Total Operating Expenses	(109)	(104)	(322)	(302)
Nonoperating Income (Expense)
Interest income	0	0	0	1
Interest expense	(2)	0	(3)	(3)
Other	1	2	4	5
Nonoperating Income (Expense) Total	(1)	2	1	3
Income before income tax	0	1	2	2
Special Revenue and Charges [Member]
Operating revenues
Passenger, Mainline	0	0	0	0
Passenger, Regional	0	0	0	0
Total passenger revenue	0	0	0	0
CPA revenues	0	0	0	0
Freight and mail	0	0	0	0
Other - net revenue	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating expenses
Operating expenses, excluding fuel	22	0	36	0
Economic fuel	3	5	9	1
Total Operating Expenses	25	5	27	(1)
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Other	0	0	0	0
Nonoperating Income (Expense) Total	0	0	0	0
Income before income tax	$ (25)	$ (5)	$ (27)	$ 1