Hedging - Foreign Currency and Fuel Derivatives Narrative (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Derivative [Line Items]
Foreign currency cash flow hedge unrealized losses that would be reclassified during next 12 months	$ 7
Bunker fuel forward contracts
Derivative [Line Items]
Maximum period for which the company locks in fuel purchase prices	3 years
Amount of unrealized net gains on bunker fuel hedging portfolio that would be reclassified to net income, if realized in the next twelve months	$ 1

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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

+ Details

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- Definition

Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

+ Details

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- Definition

The estimated net amount of unrealized gains or losses on price risk cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

+ References

+ Details

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