Securities Portfolio (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Security	Dec. 31, 2016 USD ($) Security	Dec. 31, 2015 USD ($)
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 158,192	$ 202,000
Gross unrealized gains	808	532
Gross unrealized losses	(1,879)	(3,167)
Fair value	157,121	199,365
Securities pledged as collateral	$ 66,600	72,900
Number of securities exceeding ten percent of stockholders' equity | Security	0
Available-for-Sale, Amortized Cost [Abstract]
Due in one year or less	$ 4,015
Due after one year through five years	23,293
Due after five years through ten years	38,197
Due after ten years	91,393
Total debt securities	156,898
Other securities without stated maturities	1,294
Total securities	158,192
Available-for-Sale, Fair Value [Abstract]
Due in one year or less	4,009
Due after one year through five years	23,126
Due after five years through ten years	37,997
Due after ten years	90,598
Total debt securities	155,730
Other securities without stated maturities	1,391
Fair Value	157,121
Information about securities sold [Abstract]
Proceeds from sales	4,480	107,647	$ 23,005
Gross realized gains	96	578	76
Gross realized losses	0	56	$ 0
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	112	3,166
More Than Twelve Months	1,767	1
Total	1,879	3,167
Securities Available-for-Sale, Fair Value [Abstract]
Less Than Twelve Months	25,170	129,682
More Than Twelve Months	79,434	100
Total	$ 104,604	$ 129,782
Securities Available-for-Sale, Number of Securities [Abstract]
Number of Securities | Security	77	98
U.S. Treasury Securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost		$ 20,000
Gross unrealized gains		0
Gross unrealized losses		0
Fair value		20,000
Obligations of US Government Agencies [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 9,530	9,361
Gross unrealized gains	27	0
Gross unrealized losses	(122)	(166)
Fair value	9,435	9,195
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	11	166
More Than Twelve Months	111	0
Total	122	166
Securities Available-for-Sale, Fair Value [Abstract]
Less Than Twelve Months	3,189	9,195
More Than Twelve Months	3,089	0
Total	$ 6,278	$ 9,195
Securities Available-for-Sale, Number of Securities [Abstract]
Number of Securities | Security	13	6
Obligations of State and Political Subdivisions [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 64,413	$ 78,645
Gross unrealized gains	489	358
Gross unrealized losses	(137)	(1,016)
Fair value	64,765	77,987
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	32	1,016
More Than Twelve Months	105	0
Total	137	1,016
Securities Available-for-Sale, Fair Value [Abstract]
Less Than Twelve Months	11,141	38,020
More Than Twelve Months	10,999	0
Total	$ 22,140	$ 38,020
Securities Available-for-Sale, Number of Securities [Abstract]
Number of Securities | Security	29	56
Mortgage-Backed Securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 75,906	$ 85,649
Gross unrealized gains	0	18
Gross unrealized losses	(1,610)	(1,973)
Fair value	74,296	83,694
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	67	1,973
More Than Twelve Months	1,543	0
Total	1,610	1,973
Securities Available-for-Sale, Fair Value [Abstract]
Less Than Twelve Months	9,742	80,680
More Than Twelve Months	64,554	0
Total	$ 74,296	$ 80,680
Securities Available-for-Sale, Number of Securities [Abstract]
Number of Securities | Security	24	23
Money Market Investments [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 1,194	$ 647
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	1,194	647
Corporate Bonds and Other Securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	7,049	7,598
Gross unrealized gains	195	92
Gross unrealized losses	(10)	(12)
Fair value	7,234	7,678
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	2	11
More Than Twelve Months	8	1
Total	10	12
Securities Available-for-Sale, Fair Value [Abstract]
Less Than Twelve Months	1,098	1,787
More Than Twelve Months	792	100
Total	$ 1,890	$ 1,887
Securities Available-for-Sale, Number of Securities [Abstract]
Number of Securities | Security	11	13
Other Marketable Equity Securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized cost	$ 100	$ 100
Gross unrealized gains	97	64
Gross unrealized losses	0	0
Fair value	$ 197	$ 164