Loans and Allowance - Non-accrual loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	$ 3,751	$ 3,780
Transfer into non-accrual	1,483	3,270
Transfer to REO		(240)
Loans paid down/payoffs	(947)	(1,145)
Loans brought to accrual status	(452)	(508)
Charged off	(565)	(1,406)
Balance	3,270	3,751
Consumer
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	403	623
Transfer into non-accrual	10	117
Loans paid down/payoffs	(130)	(64)
Loans brought to accrual status		(256)
Charged off	(98)	(17)
Balance	185	403
Residential Real estate
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	2,508	2,508
Transfer into non-accrual	329	1,415
Transfer to REO		(126)
Loans paid down/payoffs	(429)	(191)
Loans brought to accrual status	(281)	(252)
Charged off	(3)	(846)
Balance	2,124	2,508
Indirect
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	193	349
Transfer into non-accrual	686	898
Loans paid down/payoffs	(163)	(875)
Loans brought to accrual status	(171)
Charged off	(457)	(179)
Balance	88	193
Commercial
Financing Receivable Nonaccrual Status [Roll Forward]
Transfer into non-accrual	56
Loans paid down/payoffs	(1)
Charged off	(7)
Balance	48
Construction
Financing Receivable Nonaccrual Status [Roll Forward]
Transfer into non-accrual	402
Loans paid down/payoffs	(84)
Balance	318
Commercial Real Estate
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	647	300
Transfer into non-accrual		840
Transfer to REO		(114)
Loans paid down/payoffs	(140)	(15)
Charged off		(364)
Balance	$ 507	$ 647

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

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Represents loans returned to accrual status.

+ References

No definition available.

+ Details

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- Definition

Represents nonaccrual loan paid off.

+ References

No definition available.

+ Details

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- Definition

Represents amount transfers into non-accrual during the period.

+ References

No definition available.

+ Details

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

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- Definition

Value transferred from mortgage loans to real estate owned (REO) in noncash transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

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