XML 111 R94.htm IDEA: XBRL DOCUMENT v3.8.0.1
Deposits - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Deposits [Abstract]      
Balance of accounts with more than $250,000 balance $ 108,500,000 $ 104,700,000  
Interest expenses on accounts with more than $250,000 balance $ 545,000 $ 444,000 $ 787,000