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Income Taxes - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Income Tax Disclosure [Abstract]          
Statutory tax rate 35.00% 35.00% 35.00% 35.00%  
Effective tax rate, statutory federal rate net of discrete federal and state taxes 19.30% 5.50% 24.00% 2.40%  
Liability for uncertain tax position $ 0   $ 0   $ 0