CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 149us-gaap_NetIncomeLoss	$ 94us-gaap_NetIncomeLoss
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	7	3
Income tax effect	(3)	(1)
Total	4	2
Related to employee benefit plans:
Reclassification of net pension expense into Wages and benefits	3	2
Income tax effect	(1)us-gaap_OtherComprehensiveIncomeLossTax	(1)us-gaap_OtherComprehensiveIncomeLossTax
Total	2	1
Related to interest rate derivative instruments:
Unrealized holding gains (losses) arising during the period	(4)	(3)
Reclassification of (gains) losses into Aircraft rent	2	2
Income tax effect	1	0
Total	(1)	(1)
Other Comprehensive Income	5	2
Comprehensive Income	$ 154us-gaap_ComprehensiveIncomeNetOfTax	$ 96us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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