New Accounting Pronouncements (Details) (USD $) In Millions, except Per Share data	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Special revenue item		$ 107
Passenger Tickets [Member] | ASU 2009-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	93	254
Per basic share	$ 0.28	$ 0.77
Per diluted share	$ 0.24	$ 0.64
Co-Brand Agreement [Member] | ASU 2009-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	42	58
Per basic share	$ 0.13	$ 0.18
Per diluted share	$ 0.11	$ 0.15
Expected increase to other sales revenue per quarter		50
ASU 2009-13 [Member] | Special Revenue Item [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Special revenue item		$ 107
Per basic share		$ 0.33
Per diluted share		$ 0.27