Financial Instruments And Risk Management Financial Instruments and Risk Management (Gross and Net BS Presentation) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 58	[1]	$ 65	[1]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	[2]	0
Cash Flow Hedge Derivative Instrument, Net Assets (Liabilities), at Fair Value	58		65
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	0		0
Collateral Already Posted, Aggregate Fair Value	0	[3]	0	[3]
Cash Flow Hedge Derivative Instruments - Total, including offset	$ 58		$ 65

[1] Fuel derivative assets are included in Fuel derivative contracts on the accompanying Condensed Consolidated Balance Sheets.

[2] Fuel derivative liabilities are included in Accrued liabilities on the accompanying Condensed Consolidated Balance Sheets.

[3] Includes the effective and ineffective portion of hedge gain (loss)