OPERATING SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) airline	Mar. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Airlines | airline	2
Number of Operating Segments | airline	3
Operating revenues
Passenger, Mainline	$ 927	$ 901
Passenger, Regional	206	186
Total passenger revenue	1,133	1,087
CPA revenues	0	0
Freight and mail	24	23
Other - net revenue	190	159
Total Operating Revenues	1,347	1,269
Operating expenses
Operating expenses, excluding fuel	890	796
Economic fuel	167	235
Total Operating Expenses	1,057	1,031
Nonoperating Income (Expense)
Interest income	6	5
Interest expense	(13)	(11)
Other	9	8
Nonoperating Income (Expense) Total	2	2
Income before income tax	$ 292	240
Air Group Adjusted [Member]
Segment Reporting Information [Line Items]
Number of Airlines | airline	2
Operating revenues
Passenger, Mainline	$ 927	901
Passenger, Regional	206	186
Total passenger revenue	1,133	1,087
CPA revenues	0	0
Freight and mail	24	23
Other - net revenue	190	159
Total Operating Revenues	1,347	1,269
Operating expenses
Operating expenses, excluding fuel	890	796
Economic fuel	169	235
Total Operating Expenses	1,059	1,031
Nonoperating Income (Expense)
Interest income	6	5
Interest expense	(13)	(11)
Other	9	8
Nonoperating Income (Expense) Total	2	2
Income before income tax	290	240
Alaska Mainline [Member]
Operating revenues
Passenger, Mainline	927	901
Passenger, Regional	0	0
Total passenger revenue	927	901
CPA revenues	0	0
Freight and mail	23	22
Other - net revenue	172	142
Total Operating Revenues	1,122	1,065
Operating expenses
Operating expenses, excluding fuel	701	639
Economic fuel	144	203
Total Operating Expenses	845	842
Nonoperating Income (Expense)
Interest income	6	5
Interest expense	(12)	(7)
Other	7	7
Nonoperating Income (Expense) Total	1	5
Income before income tax	278	228
Alaska Regional [Member]
Operating revenues
Passenger, Mainline	0	0
Passenger, Regional	206	186
Total passenger revenue	206	186
CPA revenues	0	0
Freight and mail	1	1
Other - net revenue	17	16
Total Operating Revenues	224	203
Operating expenses
Operating expenses, excluding fuel	186	164
Economic fuel	25	32
Total Operating Expenses	211	196
Nonoperating Income (Expense)
Interest income	0	0
Interest expense	0	0
Other	0	0
Nonoperating Income (Expense) Total	0	0
Income before income tax	$ 13	7
Horizon [Member]
Segment Reporting Information [Line Items]
Capacity purchase arrangements	100.00%
Operating revenues
Passenger, Mainline	$ 0	0
Passenger, Regional	0	0
Total passenger revenue	0	0
CPA revenues	103	99
Freight and mail	0	0
Other - net revenue	1	1
Total Operating Revenues	104	100
Operating expenses
Operating expenses, excluding fuel	105	91
Economic fuel	0	0
Total Operating Expenses	105	91
Nonoperating Income (Expense)
Interest income	0	0
Interest expense	(1)	(4)
Other	0	1
Nonoperating Income (Expense) Total	(1)	(3)
Income before income tax	(2)	6
Intersegment Elimination [Member]
Operating revenues
Passenger, Mainline	0	0
Passenger, Regional	0	0
Total passenger revenue	0	0
CPA revenues	(103)	(99)
Freight and mail	0	0
Other - net revenue	0	0
Total Operating Revenues	(103)	(99)
Operating expenses
Operating expenses, excluding fuel	(102)	(98)
Economic fuel	0	0
Total Operating Expenses	(102)	(98)
Nonoperating Income (Expense)
Interest income	0	0
Interest expense	0	0
Other	2	0
Nonoperating Income (Expense) Total	2	0
Income before income tax	1	(1)
Special Revenue and Charges [Member]
Operating revenues
Passenger, Mainline	0	0
Passenger, Regional	0	0
Total passenger revenue	0	0
CPA revenues	0	0
Freight and mail	0	0
Other - net revenue	0	0
Total Operating Revenues	0	0
Operating expenses
Operating expenses, excluding fuel	0	0
Economic fuel	(2)	0
Total Operating Expenses	(2)	0
Nonoperating Income (Expense)
Interest income	0	0
Interest expense	0	0
Other	0	0
Nonoperating Income (Expense) Total	0	0
Income before income tax	$ 2	$ 0