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Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Income Tax Disclosure [Abstract]      
Income tax expense $ 1,692 $ 1,380  
Effective tax rate 26.00% 28.50%  
Federal Income Tax Rate 21.00%   35.00%