Loans and ALLL (Summary of changes in ALLL by segments) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	$ 8,200	$ 7,600	$ 7,700	$ 7,400
Allowance for loan losses, Charge-offs	(179)	(157)	(848)	(370)
Allowance for loan losses, Recoveries	155	208	612	585
Allowance for loan losses, Provision for loan losses	(76)	49	636	85
Allowance for loan losses, Ending Balance	8,100	7,700	8,100	7,700
Commercial [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	2,197	1,978	1,706	1,814
Allowance for loan losses, Charge-offs	(7)	(8)	(501)	(60)
Allowance for loan losses, Recoveries	80	134	284	322
Allowance for loan losses, Provision for loan losses	(249)	65	532	93
Allowance for loan losses, Ending Balance	2,021	2,169	2,021	2,169
Agricultural [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	982	475	611	884
Allowance for loan losses, Charge-offs	0	0	0	0
Allowance for loan losses, Recoveries	0	0	0	0
Allowance for loan losses, Provision for loan losses	(200)	(40)	171	(449)
Allowance for loan losses, Ending Balance	782	435	782	435
Residential Real Estate [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	2,167	2,598	2,563	2,664
Allowance for loan losses, Charge-offs	(61)	(77)	(100)	(120)
Allowance for loan losses, Recoveries	37	41	162	140
Allowance for loan losses, Provision for loan losses	239	(71)	(243)	(193)
Allowance for loan losses, Ending Balance	2,382	2,491	2,382	2,491
Consumer Portfolio Segment [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	882	583	900	624
Allowance for loan losses, Charge-offs	(111)	(72)	(247)	(190)
Allowance for loan losses, Recoveries	38	33	166	123
Allowance for loan losses, Provision for loan losses	93	89	83	76
Allowance for loan losses, Ending Balance	902	633	902	633
Unallocated [Member]
Summary of changes in the ALLL and the recorded investment in loans by segments
Allowance for loan losses, Beginning Balance	1,972	1,966	1,920	1,414
Allowance for loan losses, Charge-offs	0	0	0	0
Allowance for loan losses, Recoveries	0	0	0	0
Allowance for loan losses, Provision for loan losses	41	6	93	558
Allowance for loan losses, Ending Balance	$ 2,013	$ 1,972	$ 2,013	$ 1,972

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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- Definition

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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