Investment Securities - Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 21,449
Due after one year through five years	53,793
Due after five years through ten years	11,409
Due after ten years	8,444
Total	95,095
Mortgage-backed securities	126,072
Total available-for-sale securities	221,167	$ 222,578
Fair Value
Due in one year or less	21,361
Due after one year through five years	53,389
Due after five years through ten years	11,285
Due after ten years	8,261
Total	94,296
Mortgage-backed securities	124,243
Total available-for-sale securities	$ 218,539	$ 218,205