CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income	$ 814	$ 848	$ 605
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	1	(6)	2
Reclassification of (gains) losses into Other-net nonoperating income (expense)	(1)	1	(2)
Income tax benefit (expense)	0	2	0
Marketable securities, net of tax	0	(3)	0
Related to employee benefit plans:
Actuarial gains (losses) related to pension and other postretirement benefit plans	(43)	10	(210)
Reclassification of net pension expense into Wages and benefits	20	14	9
Income tax benefit (expense)	12	(14)	76
Total	(11)	10	(125)
Related to interest rate derivative instruments:
Unrealized holding gains (losses) arising during the period	8	(5)	(8)
Reclassification of losses into Aircraft rent	6	6	6
Income tax benefit (expense)	(5)	(1)	0
Interest rate derivative instruments, net of tax	9	0	(2)
Other comprehensive loss	(2)	7	(127)
Comprehensive income	$ 812	$ 855	$ 478