Investment Securities - Summary of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Amortized Cost
Available-for-sale: Due in one year or less	$ 2,812
Available-for-sale: Due after one year through five years	15,374
Available-for-sale: Due after five years through ten years	41,740
Available-for-sale: Due after ten years	249,138
Available-for-sale, Amortized Cost	309,064
Fair Value
Available-for-sale: Due in one year or less	2,843
Available-for-sale: Due after one year through five years	15,608
Available-for-sale: Due after five years through ten years	43,819
Available-for-sale: Due after ten years	251,750
Available-for-sale, Fair Value	314,020
Amortized Cost
Held-to-maturity: Due in one year or less	348
Held-to-maturity: Due after one year through five years	4,909
Held-to-maturity: Due after five years through ten years	20,222
Held-to-maturity: Due after ten years	77,933
Held-to-maturity, Amortized Cost	103,412	$ 116,792
Fair Value
Held-to-maturity: Due in one year or less	349
Held-to-maturity: Due after one year through five years	5,005
Held-to-maturity: Due after five years through ten years	20,948
Held-to-maturity: Due after ten years	79,707
Held-to-maturity, Fair Value	$ 106,009	$ 117,698