Investment Securities - Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized cost
Due in one year or less	$ 10,000
Due after one year through five years	10,000
Due after five years through ten years	0
Due after ten years	9,275
Mortgage and asset-backed securities	270,255
Amortized cost	299,530	$ 274,957
Fair value
Due in one year or less	10,003
Due after one year through five years	10,021
Due after five years through ten years	0
Due after ten years	9,246
Mortgage and asset-backed securities	278,255
Fair value	$ 307,525	$ 277,439