Investment Securities - Amortized Cost and Fair Value of Debt Securities (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Amortized Cost
Amortized Cost - Due in one year or less	$ 4,839
Amortized Cost - Due after one year to five years	45,064
Amortized Cost - Due after five years to ten years	54,858
Amortized Cost - Due after ten years	14,605
Amortized Cost - Total	119,366
Fair Value
Fair Value - Due in one year or less	4,836
Fair Value - Due after one year to five years	44,918
Fair Value - Due after five years to ten years	54,301
Fair Value - Due after ten years	14,775
Fair Value - Total	$ 118,830