Loans, Impaired Financing Receivable (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	$ 28,594		$ 28,594		$ 28,887
Recorded Investment With No Allowance	17,823		17,823		21,756
Recorded Investment With Allowance	7,094		7,094		2,642
Total Recorded Investment	24,917		24,917		24,398
Related Allowance	654		654		410
Average Recorded Investment	25,198	$ 24,057	24,769	$ 21,875
Interest Income Recognized	182	217	604	568
Interest Income Recognized Cash Basis	6	27	14	57
Real Estate Loans [Member] \| Mortgages [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	939		939		1,055
Recorded Investment With No Allowance	360		360		273
Recorded Investment With Allowance	466		466		700
Total Recorded Investment	826		826		973
Related Allowance	12		12		47
Average Recorded Investment	896	741	988	874
Interest Income Recognized	3	3	10	9
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Home Equity [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	108		108		92
Recorded Investment With No Allowance	12		12		40
Recorded Investment With Allowance	77		77		52
Total Recorded Investment	89		89		92
Related Allowance	15		15		9
Average Recorded Investment	92	70	98	62
Interest Income Recognized	2	1	4	3
Interest Income Recognized Cash Basis	0	0	0	0
Real Estate Loans [Member] \| Commercial [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	17,043		17,043		16,363
Recorded Investment With No Allowance	12,595		12,595		13,154
Recorded Investment With Allowance	1,553		1,553		710
Total Recorded Investment	14,148		14,148		13,864
Related Allowance	224		224		94
Average Recorded Investment	14,116	13,663	13,915	10,812
Interest Income Recognized	130	122	372	280
Interest Income Recognized Cash Basis	6	2	14	5
Real Estate Loans [Member] \| Agricultural [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	5,050		5,050		5,231
Recorded Investment With No Allowance	1,752		1,752		3,283
Recorded Investment With Allowance	3,286		3,286		618
Total Recorded Investment	5,038		5,038		3,901
Related Allowance	86		86		3
Average Recorded Investment	5,146	3,799	4,472	3,609
Interest Income Recognized	24	27	124	90
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	4	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	3,956		3,956		4,739
Recorded Investment With No Allowance	2,990		2,990		3,766
Recorded Investment With Allowance	378		378		431
Total Recorded Investment	3,368		3,368		4,197
Related Allowance	152		152		231
Average Recorded Investment	3,495	4,337	3,906	4,988
Interest Income Recognized	21	54	73	131
Interest Income Recognized Cash Basis	0	25	0	52
Other Agricultural Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	1,498		1,498		1,397
Recorded Investment With No Allowance	114		114		1,238
Recorded Investment With Allowance	1,334		1,334		125
Total Recorded Investment	1,448		1,448		1,363
Related Allowance	165		165		26
Average Recorded Investment	1,453	1,443	1,388	1,528
Interest Income Recognized	2	10	21	55
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
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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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-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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