Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Additional Information) (Detail)

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Income Taxes (Additional Information) (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Income Tax [Line Items]        
Income tax provision $ 9,766 $ 15,772 $ 48,284 $ 49,861
Effective income tax rate 35.70% 38.10% 37.50% 38.50%
Federal statutory rate     35.00%