Loans and ALLL (Summary of changes in ALLL by segments) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	$ 7,700	$ 7,400
Allowance for loan losses, Charge-offs	(103)	(144)
Allowance for loan losses, Recoveries	219	217
Allowance for loan losses, Provision for loan losses	384	27
Allowance for loan losses, Ending Balance	8,200	7,500
Commercial [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	1,706	1,814
Allowance for loan losses, Charge-offs	(5)	(27)
Allowance for loan losses, Recoveries	103	133
Allowance for loan losses, Provision for loan losses	36	(149)
Allowance for loan losses, Ending Balance	1,840	1,771
Agricultural [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	611	884
Allowance for loan losses, Charge-offs	0	0
Allowance for loan losses, Recoveries	0	0
Allowance for loan losses, Provision for loan losses	613	(357)
Allowance for loan losses, Ending Balance	1,224	527
Residential Real Estate [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	2,563	2,664
Allowance for loan losses, Charge-offs	(10)	(43)
Allowance for loan losses, Recoveries	56	36
Allowance for loan losses, Provision for loan losses	(127)	441
Allowance for loan losses, Ending Balance	2,482	3,098
Consumer Portfolio Segment [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	900	624
Allowance for loan losses, Charge-offs	(88)	(74)
Allowance for loan losses, Recoveries	60	48
Allowance for loan losses, Provision for loan losses	(77)	73
Allowance for loan losses, Ending Balance	795	671
Unallocated [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	1,920	1,414
Allowance for loan losses, Charge-offs	0	0
Allowance for loan losses, Recoveries	0	0
Allowance for loan losses, Provision for loan losses	(61)	19
Allowance for loan losses, Ending Balance	$ 1,859	$ 1,433

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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