GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NARRATIVE (Details) - Accounting Standards Update 2014-09 [Member] - Scenario, Forecast [Member] $ in Millions	Jan. 01, 2018 USD ($)
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amount of increase to the liability for earned miles	$ 350
Amount of decrease to air traffic liability	80
Overall impact on equity	170
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amount of increase to the liability for earned miles	450
Amount of decrease to air traffic liability	90
Overall impact on equity	$ 250