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Income Taxes - Additional Information (Detail) (USD $)
In Millions
12 Months Ended
Dec. 31, 2010
Jun. 30, 2011
Income Taxes [Line Items]    
Reduction in deferred tax liabilities due to statutory tax rates in Canada being lower than those in the United States $ (5.1)  
Deferred tax liabilities that have not been provided on such unremitted foreign earnings for United States Federal or state income taxes   $ 13.5