CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 234	$ 165	$ 383	$ 259
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	(5)	4	2	7
Reclassification of (gains) losses into Other-net nonoperating income (expense)	0	(1)	0	(1)
Income tax effect	2	(1)	(1)	(2)
Total	(3)	2	1	4
Related to employee benefit plans:
Reclassification of net pension expense into Wages and benefits	5	3	8	5
Income tax effect	(2)	(1)	(3)	(2)
Total	3	2	5	3
Related to interest rate derivative instruments:
Unrealized holding gains (losses) arising during the period	1	(2)	(3)	(5)
Reclassification of (gains) losses into Aircraft rent	1	1	3	3
Income tax effect	(1)	0	0	0
Total	1	(1)	0	(2)
Other Comprehensive Income	1	3	6	5
Comprehensive Income	$ 235	$ 168	$ 389	$ 264