CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net Income	$ 37	$ 41
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	(1)	4
Reclassification adjustment for gains included in net income	(1)	(1)
Income tax effect	1	(1)
Marketable securities, net of tax	(1)	2
Related to employee benefit plans:
Prior service cost arising during period	10	10
Income tax effect	(4)	(4)
Employee benefit plans, net of tax	6	6
Related to interest rate derivative instruments:
Unrealized holding gains arising during the period	3	1
Reclassification of (gain) loss into net income (within Aircraft rent)	1	2
Income tax effect	(2)	(4)
Interest rate derivative instruments, net of tax	2	(1)
Other comprehensive income	7	7
Comprehensive income	$ 44	$ 48