Securities - Contractual Maturities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due in one year or less	$ 40,247	$ 28,039
Due after one year through five years	159,444	149,487
Due after five years through ten years	15,254	22,122
Due after ten years	3,223	8,245
Amortized Cost	218,168	207,893
Estimated Fair Value
Due in one year or less	40,460	28,042
Due after one year through five years	159,571	151,102
Due after five years through ten years	15,452	22,271
Due after ten years	3,493	8,611
Fair Value	218,976	210,026
Proceeds from sales and maturities and related gains and losses
Gross realized gains		61
Gross realized losses		(26)
Net realized gains		35
Proceeds from sales of securities		917
Gross realized gains	10	17	$ 29
Net realized gains	10	17	29
Proceeds from maturities, calls and paydowns of securities	$ 41,520	$ 56,438	$ 36,450