OPERATING SEGMENT INFORMATION, ASSETS (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Total assets	$ 10,739	$ 9,962
Alaska Airlines [Member]
Total assets	16,382	15,260
Horizon [Member]
Total assets	914	690
Parent [Member]
Total assets	$ (6,557)	$ (5,988)