Condensed Consolidated Statement of Comprehensive Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
OPERATING REVENUES [Abstract]
Passenger	$ 4,046	$ 4,034	$ 12,127	$ 10,875
Freight	39	35	118	103
Other	224	242	670	572
Total operating revenues	4,309	4,311	12,915	11,550
OPERATING EXPENSES [Abstract]
Salaries, wages, and benefits	1,189	1,146	3,552	3,226
Fuel and oil	1,528	1,586	4,615	4,150
Maintenance materials and repairs	300	272	862	717
Aircraft rentals	92	90	270	214
Landing fees and other rentals	278	257	791	705
Depreciation and amortization	217	191	620	523
Acquisition and integration	145	22	168	97
Other operating expenses	509	522	1,505	1,372
Total operating expenses	4,258	4,086	12,383	11,004
OPERATING INCOME (LOSS)	51	225	532	546
OTHER EXPENSES (INCOME) [Abstract]
Interest expense	35	50	112	143
Capitalized interest	(5)	(3)	(16)	(8)
Interest income	(2)	(1)	(5)	(8)
Other (gains) losses, net	(10)	405	(119)	351
Total other expenses (income)	18	451	(28)	478
INCOME (LOSS) BEFORE INCOME TAXES	33	(226)	560	68
PROVISION (BENEFIT) FOR INCOME TAXES	17	(86)	217	42
Net income (loss)	16	(140)	343	26
Net income per share, basic	$ 0.02	$ (0.18)	$ 0.45	$ 0.03
Net income per share, diluted	$ 0.02	$ (0.18)	$ 0.45	$ 0.03
Comprehensive income (loss)	$ 211	$ (546)	$ 442	$ (225)
Weighted average shares outstanding, basic	739	792	756	773
Weighted Average Number of Shares Outstanding, Diluted	740	792	762	774
Cash dividends declared per common share (in dollars per share)	$ 0.0100	$ 0.0045	$ 0.0245	$ 0.0135