Loans (Schedule of Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 15,320	$ 15,304	$ 14,808	$ 14,438
Provision for Loan Losses	250	0	1,100	1,200
Recoveries	101	65	313	194
Loans Charged-off	(350)	(215)	(900)	(678)
Ending Balance	15,321	15,154	15,321	15,154
Commercial and Industrial Loans and Leases
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,672	4,190	3,725	4,242
Provision for Loan Losses	204	(378)	151	(453)
Recoveries	1	1	10	29
Loans Charged-off	(140)	0	(149)	(5)
Ending Balance	3,737	3,813	3,737	3,813
Commercial Real Estate Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	5,316	6,533	5,452	6,342
Provision for Loan Losses	(81)	(1,111)	(62)	(923)
Recoveries	4	2	43	5
Loans Charged-off	(6)	0	(200)	0
Ending Balance	5,233	5,424	5,233	5,424
Agricultural Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	4,829	2,704	4,094	2,115
Provision for Loan Losses	(10)	1,408	725	1,997
Recoveries	9	0	9	0
Loans Charged-off	0	(10)	0	(10)
Ending Balance	4,828	4,102	4,828	4,102
Home Equity Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	300	350	283	383
Provision for Loan Losses	37	20	70	60
Recoveries	6	1	8	2
Loans Charged-off	0	(15)	(18)	(89)
Ending Balance	343	356	343	356
Consumer Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	254	242	235	230
Provision for Loan Losses	135	119	307	212
Recoveries	78	59	205	147
Loans Charged-off	(204)	(173)	(484)	(342)
Ending Balance	263	247	263	247
Residential Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	353	559	329	414
Provision for Loan Losses	56	(7)	94	344
Recoveries	3	2	38	11
Loans Charged-off	0	(17)	(49)	(232)
Ending Balance	412	537	412	537
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	596	726	690	712
Provision for Loan Losses	(91)	(51)	(185)	(37)
Recoveries	0	0	0	0
Loans Charged-off	0	0	0	0
Ending Balance	$ 505	$ 675	$ 505	$ 675

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount, after recoveries, of loans and leases that have been written-off.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of expense related to estimated loss from loan and lease transactions.

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