Loans (Schedule of Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 15,637	$ 15,320	$ 15,694	$ 14,808
Provision for Loan Losses	500	250	2,070	1,100
Recoveries	182	101	396	313
Loans Charged-off	(268)	(350)	(2,109)	(900)
Ending Balance	16,051	15,321	16,051	15,321
Commercial and Industrial Loans and Leases
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,563	3,672	4,735	3,725
Provision for Loan Losses	(444)	204	(121)	151
Recoveries	69	1	74	10
Loans Charged-off	0	(140)	(1,500)	(149)
Ending Balance	3,188	3,737	3,188	3,737
Commercial Real Estate Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	4,958	5,316	4,591	5,452
Provision for Loan Losses	138	(81)	498	(62)
Recoveries	7	4	18	43
Loans Charged-off	(9)	(6)	(13)	(200)
Ending Balance	5,094	5,233	5,094	5,233
Agricultural Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	5,578	4,829	4,894	4,094
Provision for Loan Losses	618	(10)	1,302	725
Recoveries	20	9	20	9
Loans Charged-off	0	0	0	0
Ending Balance	6,216	4,828	6,216	4,828
Home Equity Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	366	300	330	283
Provision for Loan Losses	(80)	37	(38)	70
Recoveries	1	6	11	8
Loans Charged-off	(10)	0	(26)	(18)
Ending Balance	277	343	277	343
Consumer Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	347	254	298	235
Provision for Loan Losses	195	135	399	307
Recoveries	82	78	239	205
Loans Charged-off	(238)	(204)	(550)	(484)
Ending Balance	386	263	386	263
Residential Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	366	353	343	329
Provision for Loan Losses	67	56	68	94
Recoveries	3	3	34	38
Loans Charged-off	(11)	0	(20)	(49)
Ending Balance	425	412	425	412
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	459	596	503	690
Provision for Loan Losses	6	(91)	(38)	(185)
Recoveries	0	0	0	0
Loans Charged-off	0	0	0	0
Ending Balance	$ 465	$ 505	$ 465	$ 505

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

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-Name Accounting Standards Codification
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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.

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Amount of expense related to estimated loss from loan and lease transactions.

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