Securities (Details) $ in Thousands	Sep. 30, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Securities available for sale
Securities available for sale, Percent	100.00%	100.00%
Available-for-sale Securities Reconciliation [Abstract]
Amortized Cost	$ 297,292	$ 286,296
Gross Unrealized Gains	130	723
Gross Unrealized (Losses)	(5,120)	(1,864)
Amortized Cost
Due in one year or less	41,457
Due after one year through five years	180,463
Due after five years through ten years	74,811
Due over ten years	561
Fair Value
Due in one year or less	41,340
Due after one year through five years	177,642
Due after five years through ten years	72,759
Due over ten years	561
Carrying value of investment securities pledged to collateralize short-term borrowings	$ 292,302	$ 285,155
Less than 12 months
Number of securities \| security	402	272
Fair Value	$ 155,155	$ 134,532
Unrealized Loss	$ (2,486)	$ (1,034)
Percentage	1.60%	0.77%
12 months or more
Number of securities \| security	165	74
Fair Value	$ 90,239	$ 37,491
Unrealized Loss	$ (2,634)	$ (830)
Percentage	2.92%	2.21%
Total
Number of securities \| security	567	346
Fair Value	$ 245,394	$ 172,023
Unrealized Loss	$ (5,120)	$ (1,864)
Percentage	2.09%	1.08%
Collateralized Securities [Member]
Fair Value
Carrying value of investment securities pledged to collateralize short-term borrowings	$ 12,190
U.S. Treasury [Member]
Securities available for sale
Securities available for sale, Percent	28.18%	19.05%
Available-for-sale Securities Reconciliation [Abstract]
Amortized Cost	$ 83,949	$ 54,696
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(1,596)	(378)
Fair Value
Carrying value of investment securities pledged to collateralize short-term borrowings	$ 82,353	$ 54,318
Less than 12 months
Number of securities \| security	24	22
Fair Value	$ 58,023	$ 54,318
Unrealized Loss	$ (987)	$ (378)
Percentage	1.70%	0.70%
12 months or more
Number of securities \| security	10	0
Fair Value	$ 24,330	$ 0
Unrealized Loss	$ (609)	$ 0
Percentage	2.50%	0.00%
Total
Number of securities \| security	34	22
Fair Value	$ 82,353	$ 54,318
Unrealized Loss	$ (1,596)	$ (378)
Percentage	1.94%	0.70%
Other securities [Member]
Securities available for sale
Securities available for sale, Percent	11.88%	15.42%
Available-for-sale Securities Reconciliation [Abstract]
Amortized Cost	$ 35,398	$ 44,470
Gross Unrealized Gains	1	1
Gross Unrealized (Losses)	(666)	(512)
Fair Value
Carrying value of investment securities pledged to collateralize short-term borrowings	$ 34,733	$ 43,959
Less than 12 months
Number of securities \| security	1	9
Fair Value	$ 2,494	$ 21,411
Unrealized Loss	$ (9)	$ (83)
Percentage	0.36%	0.39%
12 months or more
Number of securities \| security	13	9
Fair Value	$ 32,239	$ 22,547
Unrealized Loss	$ (657)	$ (429)
Percentage	2.04%	1.90%
Total
Number of securities \| security	14	18
Fair Value	$ 34,733	$ 43,958
Unrealized Loss	$ (666)	$ (512)
Percentage	1.92%	1.16%
State and political subdivisions [Member]
Securities available for sale
Securities available for sale, Percent	59.94%	65.53%
Available-for-sale Securities Reconciliation [Abstract]
Amortized Cost	$ 177,945	$ 187,130
Gross Unrealized Gains	129	722
Gross Unrealized (Losses)	(2,858)	(974)
Fair Value
Carrying value of investment securities pledged to collateralize short-term borrowings	$ 175,216	$ 186,878
Less than 12 months
Number of securities \| security	377	241
Fair Value	$ 94,638	$ 58,803
Unrealized Loss	$ (1,490)	$ (573)
Percentage	1.57%	0.97%
12 months or more
Number of securities \| security	142	65
Fair Value	$ 33,670	$ 14,944
Unrealized Loss	$ (1,368)	$ (401)
Percentage	4.06%	2.68%
Total
Number of securities \| security	519	306
Fair Value	$ 128,308	$ 73,747
Unrealized Loss	$ (2,858)	$ (974)
Percentage	2.23%	1.32%

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