Loans and Allowance - Impaired financing receivables (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Recorded Investment with specific reserves	$ 28	$ 26
Unpaid Principal Balance with specific reserves	39	41
Interest Income Recognized with specific reserves	2	2
Specific Reserve with specific reserves	11	15
Recorded Investment	50	50
Recorded Investment with no specific reserve	4,876	4,627
Unpaid Principal Balance with no specific reserve	5,027	5,396
Interest Income Recognized with no specific reserve	199	109
Specific Reserve	11,000,000	15,000,000
Average Recorded Investment with no specific reserve	5,129	5,895
Consumer
Financing Receivable, Impaired [Line Items]
Recorded Investment with specific reserves	28	26
Unpaid Principal Balance with specific reserves	39	41
Interest Income Recognized with specific reserves	2	2
Specific Reserve with specific reserves	11	15
Recorded Investment	50	50
Recorded Investment with no specific reserve	34	96
Unpaid Principal Balance with no specific reserve	34	96
Interest Income Recognized with no specific reserve	4	8
Average Recorded Investment with no specific reserve	44	122
Residential real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment with no specific reserve	171	728
Unpaid Principal Balance with no specific reserve	322	1,497
Interest Income Recognized with no specific reserve		14
Average Recorded Investment with no specific reserve	544	1,928
Indirect
Financing Receivable, Impaired [Line Items]
Recorded Investment with no specific reserve	178	123
Unpaid Principal Balance with no specific reserve	178	123
Interest Income Recognized with no specific reserve	10	6
Average Recorded Investment with no specific reserve	226
Commercial \| Real Estate Loan
Financing Receivable, Impaired [Line Items]
Recorded Investment with no specific reserve	4,493	3,680
Unpaid Principal Balance with no specific reserve	4,493	3,680
Interest Income Recognized with no specific reserve	185	81
Average Recorded Investment with no specific reserve	$ 4,315	$ 3,845

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

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 (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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Amount of allowance for credit losses related to recorded investment.

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Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 310
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of interest income, recognized on cash basis, on financing receivables, for which there is no related allowance for credit losses and are recognized as impaired.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

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-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

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