Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 8,697
Amortized Cost, Due after one year through five years	27,208
Amortized Cost, Due after five years through ten years	28,533
Amortized Cost, Due after ten years	63,340
Amortized Cost, Mortgage-backed securities	65,049
Amortized Cost, Equity securities	481
Amortized Cost	193,308	$ 190,863
Fair value, Due in one year or less	8,710
Fair value, Due after one year through five years	27,523
Fair value, Due after five years through ten years	30,440
Fair value, Due after ten years	67,603
Fair value, Mortgage-backed securities	65,977
Fair value, Equity securities	714
Fair value, Total securities available for sale	$ 200,967	$ 196,249