Securities - Amortized Cost and Estimated Fair Value by Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Available-for-sale Securities, Amortized Cost
Amortized Cost	$ 252,071	$ 268,984
Available-for-sale Securities, Estimated Fair Value
Total	251,196	262,967
Held-to-maturity Securities, Amortized Cost
Total	37,649	43,503
Held-to-maturity Securities, Estimated Fair Value
Total	39,035	42,990
Mortgage-backed Securities
Available-for-sale Securities, Amortized Cost
Due within one year	0	0
Due after one through five years	7,082	7,204
Due after five through ten years	11,071	11,862
Due after ten years	120,068	139,092
Amortized Cost	138,221	158,158
Available-for-sale Securities, Estimated Fair Value
Due within one year	0	0
Due after one through five years	7,149	7,089
Due after five through ten years	11,089	11,637
Due after ten years	120,739	135,339
Total	138,977	154,065
Held-to-maturity Securities, Amortized Cost
Due within one year	0	0
Due after one through five years	354	578
Due after five through ten years	1,597	2,035
Due after ten years	28,519	28,669
Total	30,470	31,282
Held-to-maturity Securities, Estimated Fair Value
Due within one year	0	0
Due after one through five years	358	569
Due after five through ten years	1,583	1,978
Due after ten years	29,857	28,180
Total	31,798	30,727
Investment Securities
Available-for-sale Securities, Amortized Cost
Due within one year	0	0
Due after one through five years	0	0
Due after five through ten years	44,838	19,564
Due after ten years	69,012	91,262
Amortized Cost	113,850	110,826
Available-for-sale Securities, Estimated Fair Value
Due within one year	0	0
Due after one through five years	0	0
Due after five through ten years	44,367	19,362
Due after ten years	67,852	89,540
Total	112,219	108,902
Held-to-maturity Securities, Amortized Cost
Due within one year	0	0
Due after one through five years	1,094	734
Due after five through ten years	6,085	6,728
Due after ten years	0	4,759
Total	7,179	12,221
Held-to-maturity Securities, Estimated Fair Value
Due within one year	0	0
Due after one through five years	1,112	741
Due after five through ten years	6,125	6,743
Due after ten years	0	4,779
Total	$ 7,237	$ 12,263