INCOME TAXES (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Notes to Financial Statements [Abstract]
Effective income tax rate, continuing operations	35.00%
Deferred Tax Liabilities [Abstract]
Accelerated depreciation	$ 3,812	$ 3,537
Fuel derivative instruments	33	0
Other	70	84
Total deferred tax liabilities	3,915	3,621
Deferred Tax Assets, Net [Abstract]
Fuel derivative instruments	40	155
Deferred gains from sale and leaseback of aircraft	24	44
Capital and operating leases	179	141
Accrued engine maintenance	84	43
Accrued employee benefits	281	267
State taxes	77	78
Business partner income	339	207
Net operating losses and credit carrybacks	83	212
Other	170	171
Total deferred tax assets	1,277	1,318
Deferred Tax Assets (Liabilities), Net	2,638	2,303
Current:
Federal	(45)	4	198
State	12	13	19
Total current	(33)	17	217
Deferred:
Federal	287	122	61
State	10	6	8
Deferred income taxes	297	128	69
Total income tax provision	264	145	286
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax at statutory U.S. tax rates	240	114	261
Nondeductible items	10	13	8
State income taxes, net of federal benefit	14	13	18
Other	0	5	(1)
Income Tax Contingency [Line Items]
Tax periods subject to examination	2012	2011
Unrecognized Tax Benefits	5
Federal net operating loss carryforwards	230
Deferred Tax Assets, Operating Loss Carryforwards	$ 81
Federal loss carryforwards expiration date	2017 to 2031
Tax periods subject to examination	2012	2011