Condensed Consolidated Statement of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING REVENUES [Abstract]
Passenger	$ 14,735	$ 11,489	$ 9,892
Freight	139	125	118
Other	784	490	340
Total operating revenues	15,658	12,104	10,350
OPERATING EXPENSES [Abstract]
Salaries, wages, and benefits	4,371	3,704	3,468
Fuel and oil	5,644	3,620	3,044
Maintenance materials and repairs	955	751	719
Aircraft Rental	308	180	186
Landing fees and other rentals	959	807	718
Depreciation and amortization	715	628	616
Acquisition and integration	134	8	0
Other operating expenses	1,879	1,418	1,337
Total operating expenses	14,965	11,116	10,088
OPERATING INCOME (LOSS)	693	988	262
OTHER EXPENSES (INCOME) [Abstract]
Interest expense	194	167	186
Capitalized interest	(12)	(18)	(21)
Interest income	(10)	(12)	(13)
Other Nonoperating Income (Expense)	198	106	(54)
Total other expenses	370	243	98
INCOME (LOSS) BEFORE INCOME TAXES	323	745	164
PROVISION (BENEFIT) FOR INCOME TAXES	145	286	65
Net income (loss)	$ 178	$ 459	$ 99
Net income per share, basic	$ 0.23	$ 0.62	$ 0.13
Net income per share, diluted	$ 0.23	$ 0.61	$ 0.13
Cash dividends declared per common share (in dollars per share)	$ 0.0180	$ 0.0180	$ 0.0180