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 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Income Tax Disclosure [Abstract]        
Provision (benefit) for income taxes $ 6,584,000 $ (644,000) $ 17,089,000 $ (47,742,000)
Effective income tax rate 39.10% (5.10%) 36.40% (166.60%)
Net tax benefit due to change in effective tax rate   47,700,000   47,700,000
Reversal of valuation allowance on deferred tax assets   57,900,000   57,900,000
Income tax expense includes revision of deferred tax estimate from stock options and state tax $ 85,000   $ (682,000)