Allowance for Loan Losses and Credit Quality of Loans, Impaired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Allowance for Loan Losses and Credit Quality of Loans [Abstract]
Threshold balance for classified loans to be evaluated individually for impairment	$ 750
Total Loans [Abstract]
Recorded investment balance (book)	19,282	$ 21,138
Unpaid principal balance (legal)	26,991	28,120
Related allowance	25	57
Acquired impaired loans specifically evaluated for impairment	0	0
Originated Loans [Member]
With an allowance recorded [Abstract]
Recorded investment balance (book)	19,257	21,035
Unpaid principal balance (legal)	26,966	28,011
Originated Loans [Member] \| Commercial Loans [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	5,052	5,773
Unpaid principal balance (legal)	8,391	8,848
With an allowance recorded [Abstract]
Recorded investment balance (book)	25	103
Unpaid principal balance (legal)	25	109
Total Loans [Abstract]
Related allowance	25	57
Originated Loans [Member] \| Commercial Loans [Member] \| C&I [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	404
Unpaid principal balance (legal)	676
With an allowance recorded [Abstract]
Recorded investment balance (book)	25
Unpaid principal balance (legal)	25
Total Loans [Abstract]
Related allowance	25
Originated Loans [Member] \| Commercial Loans [Member] \| CRE [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	3,629
Unpaid principal balance (legal)	5,616
Originated Loans [Member] \| Commercial Loans [Member] \| Commercial [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		0
Unpaid principal balance (legal)		251
Originated Loans [Member] \| Commercial Loans [Member] \| Commercial Real Estate [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		2,211
Unpaid principal balance (legal)		3,979
With an allowance recorded [Abstract]
Recorded investment balance (book)		76
Unpaid principal balance (legal)		82
Total Loans [Abstract]
Related allowance		30
Originated Loans [Member] \| Commercial Loans [Member] \| Agricultural [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		452
Unpaid principal balance (legal)		465
With an allowance recorded [Abstract]
Recorded investment balance (book)		27
Unpaid principal balance (legal)		27
Total Loans [Abstract]
Related allowance		27
Originated Loans [Member] \| Commercial Loans [Member] \| Agricultural Real Estate [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		2,250
Unpaid principal balance (legal)		2,423
Originated Loans [Member] \| Commercial Loans [Member] \| Business Banking [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	1,019	860
Unpaid principal balance (legal)	2,099	1,730
Originated Loans [Member] \| Consumer Loans [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	7,760	8,432
Unpaid principal balance (legal)	9,854	10,383
Originated Loans [Member] \| Consumer Loans [Member] \| Dealer Finance [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	160
Unpaid principal balance (legal)	254
Originated Loans [Member] \| Consumer Loans [Member] \| Direct [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)	7,600
Unpaid principal balance (legal)	9,600
Originated Loans [Member] \| Consumer Loans [Member] \| Indirect [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		131
Unpaid principal balance (legal)		143
Originated Loans [Member] \| Consumer Loans [Member] \| Home Equity [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		8,027
Unpaid principal balance (legal)		9,966
Originated Loans [Member] \| Consumer Loans [Member] \| Direct [Member]
With no related allowance recorded [Abstract]
Recorded investment balance (book)		274
Unpaid principal balance (legal)		274
Originated Loans [Member] \| Residential Real Estate [Member]
With an allowance recorded [Abstract]
Recorded investment balance (book)	6,445	6,830
Unpaid principal balance (legal)	$ 8,721	$ 8,780

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Amount of financing receivables related to acquired loans that were individually evaluated for impairment.

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The threshold balance for classified loans to be individually evaluated for impairment.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of allowance for credit losses related to recorded investment.

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