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Financial Instruments - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2012
Derivative [Line Items]  
Fair value of interest rate swaps $ 3.2
Maximum
 
Derivative [Line Items]  
Change in fair value of interest rate swaps (0.1)
Foreign Exchange Forward
 
Derivative [Line Items]  
Fair value of the forward contracts $ (0.7)