Other Real Estate Owned and Other Repossessed Assets - Valuation Allowance Related to Real Estate Owned (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Real Estate And Foreclosed Assets [Abstract]
Beginning of period	$ 1,001	$ 1,195	$ 1,229	$ 1,423
Additions charged to expense	1	39	(25)	162
Reductions due to sales	1	(44)	(201)	(395)
End of period	$ 1,003	$ 1,190	$ 1,003	$ 1,190