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Loans and ALLL (Summary of recorded investment in loans by segments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	$ 2,503	$ 2,130
Collectively evaluated for impairment, ALLL	5,697	5,570
Total, ALLL	8,200	7,700	$ 7,500	$ 7,400
Individually evaluated for impairment, Loans	31,095	26,653
Collectively evaluated for impairment, Loans	1,061,907	1,064,866
Total	1,093,002	1,091,519
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	842	650
Collectively evaluated for impairment, ALLL	998	1,056
Total, ALLL	1,840	1,706	1,771	1,814
Individually evaluated for impairment, Loans	11,675	8,099
Collectively evaluated for impairment, Loans	631,961	626,660
Total	643,636	634,759
Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	141	0
Collectively evaluated for impairment, ALLL	1,083	611
Total, ALLL	1,224	611	527	884
Individually evaluated for impairment, Loans	11,468	10,598
Collectively evaluated for impairment, Loans	110,862	117,671
Total	122,330	128,269
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	1,520	1,480
Collectively evaluated for impairment, ALLL	962	1,083
Total, ALLL	2,482	2,563	3,098	2,664
Individually evaluated for impairment, Loans	7,940	7,939
Collectively evaluated for impairment, Loans	262,210	264,429
Total	270,150	272,368
Total Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	0	0
Collectively evaluated for impairment, ALLL	795	900
Total, ALLL	795	900	671	624
Individually evaluated for impairment, Loans	12	17
Collectively evaluated for impairment, Loans	56,874	56,106
Total	56,886	56,123
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment, ALLL	0	0
Collectively evaluated for impairment, ALLL	1,859	1,920
Total, ALLL	$ 1,859	$ 1,920	$ 1,433	$ 1,414

X

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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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 11B
-Subparagraph (h)
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
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