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Regulatory Matters - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2016
Jan. 01, 2019
Jan. 01, 2018
Jan. 01, 2017
Jan. 01, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]          
Capital conservation buffer period 4 years        
Capital conservation buffer percentage 0.625%       0.625%
Capital conservation buffer percentage maintained at bank 5.47%        
Scenario, Forecast [Member]          
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]          
Capital conservation buffer percentage   0.625% 0.625% 0.625%