Consolidated Statement of Stockholder's Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock	Capital in excess of par value	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Balance at beginning of period at Dec. 31, 2010	$ 6,237	$ 808	$ 1,183	$ 5,399	$ (262)	$ (891)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common 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 of debt	112	0	34	(27)	0	105
Net tax benefit (expense) of options exercised	(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	216	0	0	178	38	0
Balance at end of period at Dec. 31, 2011	6,877	808	1,222	5,395	(224)	(324)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	(400)	0	0	0	0	(400)
Issuance of common and treasury stock pursuant to Employee stock plans	23	0	(4)	(22)	0	49
Net tax benefit (expense) of options exercised	(24)	0	(24)	0	0	0
Share-based compensation	16	0	16	0	0	0
Cash dividends	(26)	0	0	(26)	0	0
Comprehensive income	526	0	0	421	105	0
Balance at end of period at Dec. 31, 2012	6,992	808	1,210	5,768	(119)	(675)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	(540)	0	0	0	0	(540)
Issuance of common and treasury stock pursuant to Employee stock plans	96	0	12	0	0	84
Net tax benefit (expense) of options exercised	(9)	0	(9)	0	0	0
Share-based compensation	18	0	18	0	0	0
Cash dividends	(91)	0	0	(91)	0	0
Comprehensive income	870	0	0	754	116	0
Balance at end of period at Dec. 31, 2013	$ 7,336	$ 808	$ 1,231	$ 6,431	$ (3)	$ (1,131)