Condensed Consolidated Statement of Comprehensive Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
OPERATING REVENUES [Abstract]
Passenger	$ 4,338	$ 3,892	$ 8,080	$ 6,840
Freight	42	36	79	67
Other	236	208	447	331
Total operating revenues	4,616	4,136	8,606	7,238
OPERATING EXPENSES [Abstract]
Salaries, wages, and benefits	1,222	1,125	2,363	2,078
Fuel and oil	1,577	1,527	3,087	2,565
Maintenance materials and repairs	291	246	562	444
Aircraft Rental	90	79	178	125
Landing fees and other rentals	260	247	513	448
Depreciation and amortization	202	176	403	332
Acquisition and integration	11	58	24	75
Other operating expenses	503	471	995	850
Total operating expenses	4,156	3,929	8,125	6,917
OPERATING INCOME (LOSS)	460	207	481	321
OTHER EXPENSES (INCOME) [Abstract]
Interest expense	38	51	77	94
Capitalized interest	(6)	(2)	(11)	(5)
Interest income	(2)	(4)	(3)	(7)
Other Nonoperating Income (Expense)	62	(113)	(109)	(54)
Total other expenses	92	(68)	(46)	28
INCOME (LOSS) BEFORE INCOME TAXES	368	275	527	293
PROVISION (BENEFIT) FOR INCOME TAXES	140	114	200	127
Net income (loss)	228	161	327	166
Net income per share, basic	$ 0.30	$ 0.21	$ 0.43	$ 0.22
Net income per share, diluted	$ 0.30	$ 0.21	$ 0.43	$ 0.22
Comprehensive income	$ (35)	$ (25)	$ 231	$ 321
Weighted average shares outstanding, basic	757	780	764	764
Weighted Average Number of Shares Outstanding, Diluted	764	787	771	765
Cash dividends declared per common share (in dollars per share)	$ 0.0100	$ 0.0045	$ 0.0145	$ 0.0090