Financial Instruments And Risk Management Financial Instruments and Risk Management (Effect on Statment of OCI) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
DerivativeInstruments-EffectOnStatementOfOCI [Line Items]
Amount of gain (loss) recognized in OCI on derivative	$ 34		$ 98		$ (24)		$ 16
Fuel Derivative Contracts [Member]
DerivativeInstruments-EffectOnStatementOfOCI [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	11	[1]	12	[1]	23	[1]	(13)	[1]
Amount of gain (loss) recognized in OCI on derivative	$ 23	[1]	$ 86		$ (47)		$ 29	[1]

[1] Includes the effective portion of hedge gain (loss)