Investment Securities, Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-Sale, Amortized Cost
Due within one year	$ 14,575
Due from one to five years	94,912
Due from five to ten years	97,963
Due after ten years	2,219
Amortized Cost Basis	209,669
Amortized Cost	275,081	$ 278,629
Available-for-Sale, Fair Value
Due within one year	14,576
Due from one to five years	93,591
Due from five to ten years	94,408
Due after ten years	2,096
Total available-for-sale, maturities	204,671
Available-for-sale, fair value	267,894	275,213
Held-to-Maturity, Amortized Cost
Due within one year	4,023
Due from one to five years	4,111
Due from five to ten years	8,469
Due after ten years	15,899
Amortized Cost	32,502	32,571
Held-to-Maturity, Fair Value
Due within one year	4,022
Due from one to five years	4,020
Due from five to ten years	8,261
Due after ten years	15,419
Held-to-maturity, fair value	31,722	32,350
Available-for-sale securities pledged as collateral	125,490	$ 108,751
U.S. Agency mortgage-backed securities [Member]
Available-for-Sale, Amortized Cost
Amortized Cost	65,412
Available-for-Sale, Fair Value
Available-for-sale, fair value	63,223
Held-to-Maturity, Amortized Cost
Amortized Cost	0
Held-to-Maturity, Fair Value
Held-to-maturity, fair value	$ 0