Loans, Impaired Financing Receivable (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	$ 27,990		$ 27,990		$ 20,127
Recorded Investment With No Allowance	21,676		21,676		15,031
Recorded Investment With Allowance	3,358		3,358		2,662
Total Recorded Investment	25,034		25,034		17,693
Related Allowance	457		457		487
Average Recorded Investment	24,214	$ 12,879	20,784	$ 12,838
Interest Income Recognized	229	105	351	205
Interest Income Recognized Cash Basis	17	2	30	3
Real Estate Loans [Member] \| Mortgages [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	1,246		1,246		953
Recorded Investment With No Allowance	281		281		570
Recorded Investment With Allowance	903		903		330
Total Recorded Investment	1,184		1,184		900
Related Allowance	67		67		22
Average Recorded Investment	986	460	940	425
Interest Income Recognized	3	5	6	9
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Home Equity [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	70		70		57
Recorded Investment With No Allowance	16		16		0
Recorded Investment With Allowance	54		54		57
Total Recorded Investment	70		70		57
Related Allowance	10		10		10
Average Recorded Investment	60	59	58	60
Interest Income Recognized	1	1	2	2
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Commercial [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	16,037		16,037		7,958
Recorded Investment With No Allowance	13,093		13,093		5,697
Recorded Investment With Allowance	587		587		45
Total Recorded Investment	13,680		13,680		5,742
Related Allowance	58		58		45
Average Recorded Investment	12,980	6,158	9,387	6,142
Interest Income Recognized	134	26	158	52
Interest Income Recognized Cash Basis	0	0	3	0
Real Estate Loans [Member] \| Agricultural [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	3,744		3,744		3,347
Recorded Investment With No Allowance	2,405		2,405		2,000
Recorded Investment With Allowance	1,323		1,323		1,347
Total Recorded Investment	3,728		3,728		3,347
Related Allowance	95		95		54
Average Recorded Investment	3,641	165	3,513	165
Interest Income Recognized	32	3	63	5
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Construction [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0		0
Recorded Investment With No Allowance	0		0		0
Recorded Investment With Allowance	0		0		0
Total Recorded Investment	0		0		0
Related Allowance	0		0		0
Average Recorded Investment	0	0	0	0
Interest Income Recognized	0	0	0	0
Interest Income Recognized Cash Basis	0	0	0	0
Consumer [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	4		4		0
Recorded Investment With No Allowance	2		2		0
Recorded Investment With Allowance	2		2		0
Total Recorded Investment	4		4		0
Related Allowance	2		2		0
Average Recorded Investment	3	0	2	0
Interest Income Recognized	0	0	0	0
Interest Income Recognized Cash Basis	0	0	0	0
Other Commercial Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	5,423		5,423		6,159
Recorded Investment With No Allowance	4,431		4,431		5,135
Recorded Investment With Allowance	471		471		859
Total Recorded Investment	4,902		4,902		5,994
Related Allowance	207		207		326
Average Recorded Investment	5,029	5,933	5,313	5,942
Interest Income Recognized	37	68	77	134
Interest Income Recognized Cash Basis	17	2	27	3
Other Agricultural Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	1,466		1,466		1,653
Recorded Investment With No Allowance	1,448		1,448		1,629
Recorded Investment With Allowance	18		18		24
Total Recorded Investment	1,466		1,466		1,653
Related Allowance	18		18		30
Average Recorded Investment	1,515	104	1,571	104
Interest Income Recognized	22	2	45	3
Interest Income Recognized Cash Basis	0	0	0	0
State and Political Subdivision Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0		0
Recorded Investment With No Allowance	0		0		0
Recorded Investment With Allowance	0		0		0
Total Recorded Investment	0		0		0
Related Allowance	0		0		$ 0
Average Recorded Investment	0	0	0	0
Interest Income Recognized	0	0	0	0
Interest Income Recognized Cash Basis	$ 0	$ 0	$ 0	$ 0

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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