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Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Income Tax Disclosure [Abstract]        
Effective tax rate     24.10% 34.10%
Income tax expense (benefit) $ 9,829 $ 10,208 $ 34,657 $ 39,715
Decrease in effective tax rate due to increase in domestic production activities deduction     10.00%  
Statutory tax rate, percentage     21.00%  
Excess tax benefits from stock based awards     $ 2,300 $ 1,400
Valuation allowance $ 3,100   $ 3,100  
Tax years subject to examination     2014 2015 2016 2017