Commitments And Contingencies (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012 Y employee
Commitments And Contingencies [Line Items]
Terminal improvement project amount	$ 1,000,000,000
Special facilities revenue bonds	113,000,000
Estimated construction cost	100,000,000
Project demand period that determines construction of the remaining phases, minimum years	7
Project demand period that determines construction of the remaining phases, maximum years	10
Commitment capacity available	500,000,000
Number of employees	87,000
Percentage of employees represented by various U.S. labor organizations	80.00%
Debt instrument, remaining terms (years)	10
Floating Rate Debt [Member]
Commitments And Contingencies [Line Items]
Debt instrument principal amount	2,700,000,000
Fixed Rate Debt [Member]
Commitments And Contingencies [Line Items]
Debt instrument principal amount	385,000,000
Carrying Value Of Loans/Leases From Non-U.S. Entities [Member]
Commitments And Contingencies [Line Items]
Debt instrument principal amount	$ 3,000,000,000