Investment Securities - Amortized Cost and Estimated Fair Values of Investment Securities that are Available-for-Sale and Held-to-Maturity by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available-for-sale Securities by Maturity, Amortized Cost
Available-for-sale, Securities maturing in one year or less, Amortized cost	$ 16,591
Available-for-sale, Securities maturing in After one year through five years, Amortized cost	92,971
Available-for-sale, Securities maturing in After five years through ten years, Amortized cost	58,193
Available-for-sale, Securities maturing in After ten years, Amortized cost	110,578
Available-for-sale, Amortized Cost	278,333	$ 333,268
Available-for-sale Securities by Maturity, Fair Value
Available-for-sale, Securities maturing in one year or less, Fair Value	16,680
Available-for-sale, Securities maturing in After one year through five years, Fair Value	93,642
Available-for-sale, Securities maturing in After five years through ten years, Fair Value	58,756
Available-for-sale, Securities maturing in After ten years, Fair Value	111,627
Available-for-sale, Fair Value	280,705	332,736
Held-to-maturity Securities by Maturity, Amortized Cost
Held-to-maturity, Securities maturing in one year or less, Amortized Cost	10,513
Held-to-maturity, Securities maturing in After one year through five years, Amortized Cost	39,643
Held-to-maturity, Securities maturing in After five years through ten years, Amortized Cost	11,281
Held-to-maturity, Amortized Cost	61,437	65,882
Held-to-maturity Securities by Maturity, Fair Value
Held-to-maturity, Securities maturing in one year or less, Fair Value	10,528
Held-to-maturity, Securities maturing in After one year through five years, Fair Value	40,003
Held-to-maturity, Securities maturing in After five years through ten years, Fair Value	11,519
Held-to-maturity, Fair Value	$ 62,050	$ 66,049