Consolidated Statement of Stockholder's Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Opening Balance at Dec. 31, 2008	$ 4,941	$ 808	$ 1,215	$ 4,907	$ (984)	$ (1,005)
Issuance of common and treasury stock pursuant to Employee stock plans	20	0	0	(22)	0	42
Net tax benefit (expense) of options excercised	(13)	0	(13)	0	0	0
Share-based compensation	14	0	14	0	0	0
Cash dividends	(13)	0	0	(13)	0	0
Comprehensive income (loss) [Abstract]
Net Income	99	0	0	99	0	0
Unrealized gain (loss) on derivative instruments	366	0	0	0	366	0
Other gain (loss)	40	0	0	0	40	0
Total comprehensive income	505
Closing Balance at Dec. 31, 2009	5,454	808	1,216	4,971	(578)	(963)
Issuance of common and treasury stock pursuant to Employee stock plans	54	0	0	(18)	0	72
Net tax benefit (expense) of options excercised	(45)	0	(45)	0	0	0
Share-based compensation	12	0	12	0	0	0
Cash dividends	(13)	0	0	(13)	0	0
Comprehensive income (loss) [Abstract]
Net Income	459	0	0	459	0	0
Unrealized gain (loss) on derivative instruments	330	0	0	0	330	0
Other gain (loss)	(14)	0	0	0	(14)	0
Total comprehensive income	775
Closing Balance at Dec. 31, 2010	6,237	808	1,183	5,399	(262)	(891)
Purchase of shares of treasury stock	(225)	0	0	0	0	(225)
Issuance of common and treasury stock pursuant to Employee stock plans	20	0	(3)	(14)	0	37
Issuance of stock to acquire AirTran	523	0	0	(127)	0	650
Issuance of stock for conversion debt	112	0	34	(27)	0	105
Net tax benefit (expense) of options excercised	(5)	0	(5)	0	0	0
Share-based compensation	13	0	13	0	0	0
Cash dividends	(14)	0	0	(14)	0	0
Comprehensive income (loss) [Abstract]
Net Income	178	0	0	178	0	0
Unrealized gain (loss) on derivative instruments	67	0	0	0	67	0
Other gain (loss)	(29)	0	0	0	(29)	0
Total comprehensive income	216
Closing Balance at Dec. 31, 2011	$ 6,877	$ 808	$ 1,222	$ 5,395	$ (224)	$ (324)