INCOME TAXES - DEFERRED TAX ASSETS AND LIABILITIES (DETAILS) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Excess of tax over book depreciation	$ 842	$ 795
Other—net	19	17
Gross deferred tax liabilities	861	812
Mileage Plan	(265)	(242)
AMT and other tax credits	(1)	(53)
Inventory obsolescence	(15)	(13)
Deferred gains	(13)	(14)
Employee benefits	(230)	(218)
Loss carryforwards	0	(13)
Fuel hedge contracts	(18)	(3)
Other—net	(21)	(27)
Gross deferred tax assets	563	583
Net deferred tax liabilities	298	229
Current deferred tax asset	(148)	(134)
Noncurrent deferred tax liability	$ 446	$ 363