INCOME TAXES - DEFERRED TAX ASSETS AND LIABILITIES (DETAILS) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Excess of tax over book depreciation	$ 919	$ 842
Other—net	21	19
Gross deferred tax liabilities	940	861
Mileage Plan	(185)	(265)
AMT and other tax credits	0	(1)
Inventory obsolescence	(18)	(15)
Deferred gains	(12)	(13)
Employee benefits	(85)	(230)
Fuel hedge contracts	(14)	(18)
Other—net	(30)	(21)
Gross deferred tax assets	344	563
Net deferred tax liabilities	596	298
Current deferred tax asset	(113)	(148)
Noncurrent deferred tax liability	$ 709	$ 446