CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (232)	$ 4
Related to marketable securities:
Unrealized holding gain (loss) arising during the period	(1)	14
Reclassification of (gain) loss into Other - net nonoperating income (expense)	(3)	2
Income tax effect	1	(4)
Total	(3)	12
Related to employee benefit plans:
Reclassification of net pension expense into Wages and benefits and Other - net nonoperating income (expense)	7	8
Income tax effect	(2)	(2)
Total	5	6
Related to interest rate derivative instruments:
Unrealized holding gain (loss) arising during the period	(25)	(5)
Reclassification of loss into Aircraft rent	1	1
Income tax effect	5	1
Total	(19)	(3)
Other Comprehensive Income (Loss)	(17)	15
Comprehensive Income (Loss)	$ (249)	$ 19