Securities - Amortized Cost and Fair Value of Debt Securities, by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, One year or less	$ 16,638
Amortized Cost, After one year through five years	119,625
Amortized Cost, After five years through ten years	52,489
Amortized Cost, After ten years	3,264
Amortized Cost, Total	192,016
Amortized Cost, Mortgage-backed securities	29,986
Amortized Cost	222,002	$ 234,793
Fair Value, One year or less	16,660
Fair Value, After one year through five years	120,549
Fair Value, After five years through ten years	53,310
Fair Value, After ten years	3,564
Fair Value, Total	194,083
Fair Value, Mortgage-backed securities	30,390
Total, Fair Value	$ 224,473	$ 235,115