Securities - Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contractual Maturities, Amortized Cost
Within one year	$ 16,248	$ 179,323
After one through five years	246,533	72,470
After five through ten years	1,587	7,087
After ten years	7,923	11,956
Amortized Costs, Gross	272,291	270,836
Amortized Costs, Net	307,808	331,529
Contractual Maturities, Fair Value
Within one year	16,247	178,581
After one through five years	246,480	72,282
After five through ten years	1,686	7,203
After ten years	8,500	12,137
Fair Value, Gross	272,913	270,203
Fair Value, Net	308,673	331,071
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	137,662	240,155
Mortgage-backed - Government-sponsored entity (GSE) - residential
Contractual Maturities, Amortized Cost
Amortized Costs, Mortgage-backed - Government-sponsored entity (GSE) - residential	35,517	60,693
Amortized Costs, Net	35,517	60,693
Contractual Maturities, Fair Value
Fair Value, Mortgage-backed - Government-sponsored entity (GSE) - residential	35,760	60,868
Fair Value, Net	35,760	60,868
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 1,114	$ 15,543