Investments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) Security	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Security	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Debt Securities [Abstract]
Amortized cost	$ 244,302		$ 244,302
Gross unrealized gains	118		118
Gross unrealized losses	(3,994)		(3,994)
Fair value	$ 240,426		$ 240,426		$ 254,782
Equity Securities [Abstract]
Amortized cost					92
Gross unrealized gains					0
Gross unrealized losses					(1)
Fair value					91
Total Available-for-sale Securities [Abstract]
Amortized cost					255,122
Gross unrealized gains					948
Gross unrealized losses					(1,288)
Fair value					254,782
Number of securities owned with fair value less than cost | Security	143		143
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	$ 131,051		$ 131,051
Twelve months or greater, Fair value	72,991		72,991
Total, Fair value	204,042		204,042
Less than twelve months, Gross unrealized losses	(2,165)		(2,165)
Twelve months or greater, Gross unrealized losses	(1,829)		(1,829)
Total, Gross Unrealized Losses	(3,994)		(3,994)
Available-for-sale Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value					145,686
Twelve months or greater, Fair value					36,708
Total, Fair value					182,394
Less than twelve months, Gross unrealized losses					(875)
Twelve months or greater, Gross unrealized losses					(413)
Total, Gross Unrealized Losses					(1,288)
Proceeds from sale of securities available-for-sale	25,168	$ 0	25,168	$ 30,393
Realized investment gains (losses) [Abstract]
Gross gains on available for sale securities	161	9	161	211
Gross losses on available for sale securities	(169)	0	(169)	(7)
Net gains	(8)	9	(8)	204
Equity Securities Fv Ni Gain (Loss) [Abstract]
Net gains (losses) recognized in equity securities during the period	(4)	$ 0	9	$ 0
Less: Net gains realized on the sale of equity securities during the period	0		0
Net unrealized gains (losses)	(4)		9
Investment securities pledged as collateral	237,000		237,000		243,400
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Due in one year or less	29,087		29,087
Due after one year through five years	105,536		105,536
Due after five years through ten years	59,609		59,609
Due after ten years	50,070		50,070
Amortized cost	244,302		244,302
Available-for-Sale Debt Securities, Fair Value [Abstract]
Due in one year or less	29,035		29,035
Due after one year through five years	103,350		103,350
Due after five years through ten years	58,574		58,574
Due after ten years	49,467		49,467
Fair value	240,426		240,426		254,782
U.S. Agency Securities [Member]
Debt Securities [Abstract]
Amortized cost	109,612		109,612		99,454
Gross unrealized gains	0		0		26
Gross unrealized losses	(1,343)		(1,343)		(593)
Fair value	108,269		108,269		98,887
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	54,399		54,399		74,952
Twelve months or greater, Fair value	40,554		40,554		16,928
Total, Fair value	94,953		94,953		91,880
Less than twelve months, Gross unrealized losses	(656)		(656)		(421)
Twelve months or greater, Gross unrealized losses	(687)		(687)		(172)
Total, Gross Unrealized Losses	(1,343)		(1,343)		(593)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	109,612		109,612		99,454
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	108,269		108,269		98,887
U.S. Treasury Securities [Member]
Debt Securities [Abstract]
Amortized cost	33,798		33,798		28,782
Gross unrealized gains	0		0		0
Gross unrealized losses	(961)		(961)		(178)
Fair value	32,837		32,837		28,604
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	32,837		32,837		28,604
Twelve months or greater, Fair value	0		0		0
Total, Fair value	32,837		32,837		28,604
Less than twelve months, Gross unrealized losses	(961)		(961)		(178)
Twelve months or greater, Gross unrealized losses	0		0		0
Total, Gross Unrealized Losses	(961)		(961)		(178)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	33,798		33,798		28,782
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	32,837		32,837		28,604
Obligations of State and Political Subdivisions [Member]
Debt Securities [Abstract]
Amortized cost	51,941		51,941		78,409
Gross unrealized gains	116		116		820
Gross unrealized losses	(459)		(459)		(139)
Fair value	51,598		51,598		79,090
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	26,648		26,648		14,885
Twelve months or greater, Fair value	8,381		8,381		5,958
Total, Fair value	35,029		35,029		20,843
Less than twelve months, Gross unrealized losses	(249)		(249)		(85)
Twelve months or greater, Gross unrealized losses	(210)		(210)		(54)
Total, Gross Unrealized Losses	(459)		(459)		(139)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	51,941		51,941		78,409
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	51,598		51,598		79,090
Corporate Obligations [Member]
Debt Securities [Abstract]
Amortized cost	3,000		3,000		3,000
Gross unrealized gains	0		0		83
Gross unrealized losses	0		0		0
Fair value	3,000		3,000		3,083
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	3,000		3,000		3,000
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	3,000		3,000		3,083
Mortgage-backed Securities in Government Sponsored Entities [Member]
Debt Securities [Abstract]
Amortized cost	45,951		45,951		45,385
Gross unrealized gains	2		2		19
Gross unrealized losses	(1,231)		(1,231)		(377)
Fair value	44,722		44,722		45,027
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	17,167		17,167		27,154
Twelve months or greater, Fair value	24,056		24,056		13,822
Total, Fair value	41,223		41,223		40,976
Less than twelve months, Gross unrealized losses	(299)		(299)		(190)
Twelve months or greater, Gross unrealized losses	(932)		(932)		(187)
Total, Gross Unrealized Losses	(1,231)		(1,231)		(377)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	45,951		45,951		45,385
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	$ 44,722		$ 44,722		45,027
Equity Securities in Financial Institutions [Member]
Available-for-sale Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value					91
Twelve months or greater, Fair value					0
Total, Fair value					91
Less than twelve months, Gross unrealized losses					(1)
Twelve months or greater, Gross unrealized losses					0
Total, Gross Unrealized Losses					$ (1)