CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Income	$ 437	$ 960	$ 797
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	(14)	(4)	1
Reclassification of (gains) losses into Other-net nonoperating income (expense)	8	1	(1)
Income tax benefit	2	1	0
Marketable securities, net of tax	(4)	(2)	0
Related to employee benefit plans:
Actuarial losses related to pension and other postretirement benefit plans	(34)	(123)	(43)
Reclassification of net pension expense into Wages and benefits and Other-net nonoperating income (expense)	28	22	20
Income tax benefit	2	24	12
Employee benefit plans, net of tax	(4)	(77)	(11)
Related to interest rate derivative instruments:
Unrealized holding gains (losses) arising during the period	0	1	8
Reclassification of losses into Aircraft rent	3	5	6
Income tax expense	(1)	(2)	(5)
Interest rate derivative instruments, net of tax	2	4	9
Other comprehensive income (loss)	(6)	(75)	(2)
Comprehensive income	$ 431	$ 885	$ 795