Schedule of Information Related to Amounts Recorded Related to Frequent Flyer Program (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Significant Accounting Policies [Line Items]
Cash Proceeds from Miles Sold	$ 2,861		$ 2,903		$ 2,852
Other Revenue Recognized Upon Award of Miles to Third-Party Customers	882	[1]	903	[1]	816	[1]
Increase in Frequent Flyer Deferred Revenue for Miles Awarded	2,178	[2]	2,174	[2]	2,036	[2]
Increase (Decrease) in Advanced Purchase of Miles	$ (199)	[3]	$ (174)	[3]

[1] This amount represents other revenue recognized during the period from the sale of miles to third parties, representing the marketing-related deliverable services component of the sale.

[2] This amount represents the increase to frequent flyer deferred revenue during the period.

[3] This amount represents the net increase (decrease) in the advance purchase of miles obligation due to cash payments for the sale of miles in excess of (less than) miles awarded to customers.