Restrictions on Cash and Due from Banks and Interest-earning Deposit Accounts - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Reserve requirement at Federal Reserve Bank	$ 4,200	$ 2,500
Average balances at Federal Reserve Bank	36,500	31,500
Pledging requirement for risk participation agreements and SWAP agreements	$ 460	$ 670