Accounting Changes And New Accounting Pronouncements (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Revenue	$ 303	$ 303
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	$ 161	$ 161
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Basic Earnings Per Share	$ 0.25	$ 0.24
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share	$ 0.24	$ 0.24
Passenger Revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Current Period Disclosures, Revenue Recognized, Amount	$ (40)	$ (40)
Special Revenue Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Current Period Disclosures, Revenue Recognized, Amount	172	172
Other Revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Current Period Disclosures, Revenue Recognized, Amount	$ 171	$ 171