Airtran Acquisitions and Related Matters (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		9 Months Ended
	May 02, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Combinations [Abstract]
Date entered into Merger Agreement	May 02, 2011
Name of acquired entity	AirTran Holdings, Inc.
Acquisition and integration		$ 28	$ 145	$ 66	$ 168