Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

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Income Taxes - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Dec. 31, 2012
Income Tax Expense (Benefit), Continuing Operations [Abstract]      
Income tax expense $ 14,902,000 $ 1,981,000  
Effective tax rate 35.90% 38.10%  
Federal statutory rate 35.00%    
Income tax receivable 45,638,000   47,884,000
Accrued taxes payable 2,200,000    
2012 estimated payments
     
Income Tax Expense (Benefit), Continuing Operations [Abstract]      
Income tax receivable 4,900,000    
tax loss carrybacks to 2010 and 2011
     
Income Tax Expense (Benefit), Continuing Operations [Abstract]      
Income tax receivable $ 42,900,000