Investments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) Security	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Security	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Debt Securities [Abstract]
Amortized cost	$ 252,938		$ 252,938
Gross unrealized gains	512		512
Gross unrealized losses	(3,425)		(3,425)
Fair value	$ 250,025		$ 250,025		$ 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	201		201
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	$ 157,633		$ 157,633
Twelve months or greater, Fair value	43,526		43,526
Total, Fair value	201,159		201,159
Less than twelve months, Gross unrealized losses	(2,388)		(2,388)
Twelve months or greater, Gross unrealized losses	(1,037)		(1,037)
Total, Gross Unrealized Losses	(3,425)		(3,425)
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	0	$ 6,641	0	$ 25,407
Realized investment gains (losses) [Abstract]
Gross gains on available for sale securities	0	30	0	202
Gross losses on available for sale securities	0	(7)	0	(7)
Net gains	0	23	0	195
Equity Securities Fv Ni Gain (Loss) [Abstract]
Net gains recognized in equity securities during the period	7	$ 0	13	$ 0
Less: Net gains realized on the sale of equity securities during the period	0		0
Unrealized gains recognized in equity securities held at reporting date	7		13
Investment securities pledged as collateral	240,800		240,800		243,400
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Due in one year or less	47,012		47,012
Due after one year through five years	106,241		106,241
Due after five years through ten years	50,336		50,336
Due after ten years	49,349		49,349
Amortized cost	252,938		252,938
Available-for-Sale Debt Securities, Fair Value [Abstract]
Due in one year or less	47,121		47,121
Due after one year through five years	104,395		104,395
Due after five years through ten years	49,644		49,644
Due after ten years	48,865		48,865
Fair value	250,025		250,025		254,782
U.S. Agency Securities [Member]
Debt Securities [Abstract]
Amortized cost	103,190		103,190		99,454
Gross unrealized gains	30		30		26
Gross unrealized losses	(1,232)		(1,232)		(593)
Fair value	101,988		101,988		98,887
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	76,159		76,159		74,952
Twelve months or greater, Fair value	19,842		19,842		16,928
Total, Fair value	96,001		96,001		91,880
Less than twelve months, Gross unrealized losses	(978)		(978)		(421)
Twelve months or greater, Gross unrealized losses	(254)		(254)		(172)
Total, Gross Unrealized Losses	(1,232)		(1,232)		(593)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	103,190		103,190		99,454
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	101,988		101,988		98,887
U.S. Treasury Securities [Member]
Debt Securities [Abstract]
Amortized cost	33,783		33,783		28,782
Gross unrealized gains	0		0		0
Gross unrealized losses	(791)		(791)		(178)
Fair value	32,992		32,992		28,604
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	32,992		32,992		28,604
Twelve months or greater, Fair value	0		0		0
Total, Fair value	32,992		32,992		28,604
Less than twelve months, Gross unrealized losses	(791)		(791)		(178)
Twelve months or greater, Gross unrealized losses	0		0		0
Total, Gross Unrealized Losses	(791)		(791)		(178)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	33,783		33,783		28,782
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	32,992		32,992		28,604
Obligations of State and Political Subdivisions [Member]
Debt Securities [Abstract]
Amortized cost	67,763		67,763		78,409
Gross unrealized gains	456		456		820
Gross unrealized losses	(347)		(347)		(139)
Fair value	67,872		67,872		79,090
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	22,564		22,564		14,885
Twelve months or greater, Fair value	6,007		6,007		5,958
Total, Fair value	28,571		28,571		20,843
Less than twelve months, Gross unrealized losses	(220)		(220)		(85)
Twelve months or greater, Gross unrealized losses	(127)		(127)		(54)
Total, Gross Unrealized Losses	(347)		(347)		(139)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	67,763		67,763		78,409
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	67,872		67,872		79,090
Corporate Obligations [Member]
Debt Securities [Abstract]
Amortized cost	3,000		3,000		3,000
Gross unrealized gains	23		23		83
Gross unrealized losses	0		0		0
Fair value	3,023		3,023		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	3,023		3,023		3,083
Mortgage-backed Securities in Government Sponsored Entities [Member]
Debt Securities [Abstract]
Amortized cost	45,202		45,202		45,385
Gross unrealized gains	3		3		19
Gross unrealized losses	(1,055)		(1,055)		(377)
Fair value	44,150		44,150		45,027
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	25,918		25,918		27,154
Twelve months or greater, Fair value	17,677		17,677		13,822
Total, Fair value	43,595		43,595		40,976
Less than twelve months, Gross unrealized losses	(399)		(399)		(190)
Twelve months or greater, Gross unrealized losses	(656)		(656)		(187)
Total, Gross Unrealized Losses	(1,055)		(1,055)		(377)
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Amortized cost	45,202		45,202		45,385
Available-for-Sale Debt Securities, Fair Value [Abstract]
Fair value	$ 44,150		$ 44,150		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)