Significant Accounting Policies (Description Of New Accounting Pronouncements Changes In Revenue) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2011
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating revenue		$ 340
Special revenue item	107	107
Per basic share		$ 1.03
Per diluted share		$ 0.89
Co-Brand Agreement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating revenue		260
Per basic share		$ 0.79
Per diluted share		$ 0.68
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		$ 0.28
Frequent Flyer [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Frequent flyer deferred revenue		5,658
Percentage of miles earned expected to expire or go unredeemed		24.00%
Impact of 1% change in outstanding miles or estimated selling price on deferred revenue		$ 74
Impact of 1% change in outstanding miles		1.00%
ASU 2009-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of elements identified in the agreement		5