Condensed Consolidated Statement of Comprehensive Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
OPERATING REVENUES [Abstract]
Passenger	$ 3,744	$ 2,949
Freight	37	31
Other	210	123
Total operating revenues	3,991	3,103
OPERATING EXPENSES [Abstract]
Salaries, wages, and benefits	1,141	954
Fuel and oil	1,510	1,038
Maintenance materials and repairs	272	199
Aircraft Rental	88	46
Landing fees and other rentals	254	201
Depreciation and amortization	201	155
Acquisition and integration	13	17
Other operating expenses	490	379
Total operating expenses	3,969	2,989
OPERATING INCOME (LOSS)	22	114
OTHER EXPENSES (INCOME) [Abstract]
Interest expense	40	43
Capitalized interest	(5)	(3)
Interest income	(2)	(3)
Other Nonoperating Income (Expense)	(170)	59
Total other expenses	(137)	96
INCOME (LOSS) BEFORE INCOME TAXES	159	18
PROVISION (BENEFIT) FOR INCOME TAXES	61	13
Net income (loss)	98	5
Net income per share, basic	$ 0.13	$ 0.01
Net income per share, diluted	$ 0.13	$ 0.01
Comprehensive income	$ 265	$ 346
Weighted average shares outstanding, basic	771	748
Weighted average number of shares outstanding, diluted	772	749
Cash dividends declared per common share (in dollars per share)	$ 0.0045	$ 0.0045