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Effects of Foreign Currency Forward Contracts Which Were Not Designated as Hedging Instruments (Detail)

v2.4.0.8
Effects of Foreign Currency Forward Contracts Which Were Not Designated as Hedging Instruments (Detail) (Not Designated as Hedging Instrument, Fuel Options, USD $)
In Thousands, unless otherwise specified
 6 Months Ended 12 Months Ended
Jun. 30, 2013
Dec. 31, 2012
Dec. 31, 2011
Not Designated as Hedging Instrument | Fuel Options
      
Derivative Instruments, Gain (Loss) [Line Items]      
Gain recognized in other income (expense) $ 20 $ 3,218 $ 2,422