OPERATING SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) airline	Jun. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Airlines | airline			2
Number of Operating Segments | airline			3
Operating revenues
Passenger, Mainline	$ 1,036	$ 1,019	$ 1,963	$ 1,920
Passenger, Regional	227	212	433	398
Total passenger revenue	1,263	1,231	2,396	2,318
CPA revenues	0	0	0	0
Freight and mail	27	30	51	53
Other - net revenue	204	176	394	335
Total Operating Revenues	1,494	1,437	2,841	2,706
Operating expenses
Operating expenses, excluding fuel	875	804	1,765	1,600
Economic fuel	201	261	368	496
Total Operating Expenses	1,076	1,065	2,133	2,096
Nonoperating Income (Expense)
Interest income	7	6	13	11
Interest expense	(9)	(11)	(22)	(22)
Other	4	9	13	17
Nonoperating Income (Expense) Total	2	4	4	6
Income before income tax	420	376	$ 712	616
Air Group Adjusted [Member]
Segment Reporting Information [Line Items]
Number of Airlines | airline			2
Operating revenues
Passenger, Mainline	1,036	1,019	$ 1,963	1,920
Passenger, Regional	227	212	433	398
Total passenger revenue	1,263	1,231	2,396	2,318
CPA revenues	0	0	0	0
Freight and mail	27	30	51	53
Other - net revenue	204	176	394	335
Total Operating Revenues	1,494	1,437	2,841	2,706
Operating expenses
Operating expenses, excluding fuel	861	804	1,751	1,600
Economic fuel	211	267	380	502
Total Operating Expenses	1,072	1,071	2,131	2,102
Nonoperating Income (Expense)
Interest income	7	6	13	11
Interest expense	(9)	(11)	(22)	(22)
Other	4	9	13	17
Nonoperating Income (Expense) Total	2	4	4	6
Income before income tax	424	370	714	610
Alaska Mainline [Member]
Operating revenues
Passenger, Mainline	1,036	1,019	1,963	1,920
Passenger, Regional	0	0	0	0
Total passenger revenue	1,036	1,019	1,963	1,920
CPA revenues	0	0	0	0
Freight and mail	26	28	49	50
Other - net revenue	184	156	356	298
Total Operating Revenues	1,246	1,203	2,368	2,268
Operating expenses
Operating expenses, excluding fuel	679	645	1,380	1,284
Economic fuel	180	232	324	436
Total Operating Expenses	859	877	1,704	1,720
Nonoperating Income (Expense)
Interest income	6	5	12	10
Interest expense	(4)	(7)	(16)	(14)
Other	3	7	10	14
Nonoperating Income (Expense) Total	5	5	6	10
Income before income tax	392	331	670	558
Alaska Regional [Member]
Operating revenues
Passenger, Mainline	0	0	0	0
Passenger, Regional	227	212	433	398
Total passenger revenue	227	212	433	398
CPA revenues	0	0	0	0
Freight and mail	1	2	2	3
Other - net revenue	19	19	36	35
Total Operating Revenues	247	233	471	436
Operating expenses
Operating expenses, excluding fuel	192	169	378	333
Economic fuel	31	35	56	66
Total Operating Expenses	223	204	434	399
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	$ 24	29	$ 37	37
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	110	99	213	198
Freight and mail	0	0	0	0
Other - net revenue	1	1	2	2
Total Operating Revenues	111	100	215	200
Operating expenses
Operating expenses, excluding fuel	101	90	206	181
Economic fuel	0	0	0	0
Total Operating Expenses	101	90	206	181
Nonoperating Income (Expense)
Interest income	1	0	1	0
Interest expense	(4)	(1)	(5)	(5)
Other	0	(1)	0	0
Nonoperating Income (Expense) Total	(3)	(2)	(4)	(5)
Income before income tax	7	8	5	14
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	(110)	(99)	(213)	(198)
Freight and mail	0	0	0	0
Other - net revenue	0	0	0	0
Total Operating Revenues	(110)	(99)	(213)	(198)
Operating expenses
Operating expenses, excluding fuel	(111)	(100)	(213)	(198)
Economic fuel	0	0	0	0
Total Operating Expenses	(111)	(100)	(213)	(198)
Nonoperating Income (Expense)
Interest income	0	1	0	1
Interest expense	(1)	(3)	(1)	(3)
Other	1	3	3	3
Nonoperating Income (Expense) Total	0	1	2	1
Income before income tax	1	2	2	1
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	14	0	14	0
Economic fuel	(10)	(6)	(12)	(6)
Total Operating Expenses	4	(6)	2	(6)
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	$ (4)	$ 6	$ (2)	$ 6