Loans, Impaired Financing Receivable (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	$ 29,038		$ 29,038		$ 28,887
Recorded Investment With No Allowance	21,212		21,212		21,756
Recorded Investment With Allowance	4,319		4,319		2,642
Total Recorded Investment	25,531		25,531		24,398
Related Allowance	405		405		410
Average Recorded Investment	24,567	$ 24,214	24,554	$ 20,784
Interest Income Recognized	208	229	422	351
Interest Income Recognized Cash Basis	3	17	8	30
Real Estate Loans [Member] \| Mortgages [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	1,138		1,138		1,055
Recorded Investment With No Allowance	261		261		273
Recorded Investment With Allowance	776		776		700
Total Recorded Investment	1,037		1,037		973
Related Allowance	15		15		47
Average Recorded Investment	1,045	986	1,034	940
Interest Income Recognized	3	3	7	6
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Home Equity [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	111		111		92
Recorded Investment With No Allowance	14		14		40
Recorded Investment With Allowance	80		80		52
Total Recorded Investment	94		94		92
Related Allowance	15		15		9
Average Recorded Investment	95	60	101	58
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	16,576		16,576		16,363
Recorded Investment With No Allowance	12,442		12,442		13,154
Recorded Investment With Allowance	1,349		1,349		710
Total Recorded Investment	13,791		13,791		13,864
Related Allowance	159		159		94
Average Recorded Investment	13,833	12,980	13,814	9,387
Interest Income Recognized	120	134	242	158
Interest Income Recognized Cash Basis	3	0	8	3
Real Estate Loans [Member] \| Agricultural [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	5,210		5,210		5,231
Recorded Investment With No Allowance	3,648		3,648		3,283
Recorded Investment With Allowance	1,556		1,556		618
Total Recorded Investment	5,204		5,204		3,901
Related Allowance	25		25		3
Average Recorded Investment	4,185	3,641	4,135	3,513
Interest Income Recognized	49	32	100	63
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	0		0		10
Recorded Investment With No Allowance	0		0		2
Recorded Investment With Allowance	0		0		6
Total Recorded Investment	0		0		8
Related Allowance	0		0		0
Average Recorded Investment	0	3	2	2
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	4,489		4,489		4,739
Recorded Investment With No Allowance	3,552		3,552		3,766
Recorded Investment With Allowance	382		382		431
Total Recorded Investment	3,934		3,934		4,197
Related Allowance	151		151		231
Average Recorded Investment	4,067	5,029	4,112	5,313
Interest Income Recognized	26	37	52	77
Interest Income Recognized Cash Basis	0	17	0	27
Other Agricultural Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	1,514		1,514		1,397
Recorded Investment With No Allowance	1,295		1,295		1,238
Recorded Investment With Allowance	176		176		125
Total Recorded Investment	1,471		1,471		1,363
Related Allowance	40		40		26
Average Recorded Investment	1,342	1,515	1,356	1,571
Interest Income Recognized	9	22	19	45
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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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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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-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
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-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

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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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