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Income Taxes - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Income Taxes [Line Items]    
Provision (benefit) for income taxes $ 300,000 $ 5,200,000
Effective income tax rate 1.10% 24.50%
Provision (benefit) for income taxes 300,000 (5,192,000)
Discrete tax benefits | Reduction of Uncertain Tax Positions
   
Income Taxes [Line Items]    
Provision (benefit) for income taxes 73,000  
Discrete tax benefits | State tax apportionment changes and an adjustment
   
Income Taxes [Line Items]    
Provision (benefit) for income taxes   $ 400,000