Loans - Credit Risk Rating for Commercial, Construction and Non-Consumer Related Loans (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) rating	Dec. 31, 2019 USD ($)
Receivables [Abstract]
Number of risk rating approaches | rating	2
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	$ 651,736	$ 588,646
Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	65,758	45,278
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	264,013	245,183
Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	45,722	45,881
Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	114	173
Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	171,889	138,784
Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	51,587	52,197
Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	553,247	481,442
Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	62,415	69,878
Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	108,251	115,932
Grades 1 and 2 | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	26,154	278
Grades 1 and 2 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	2,754	2,806
Grades 1 and 2 | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grades 1 and 2 | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	30	0
Grades 1 and 2 | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	28,938	3,084
Grade 3 | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 3 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	735	981
Grade 3 | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 3 | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 3 | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	735	981
Grades 4 and 5 – pass | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	37,135	41,757
Grades 4 and 5 – pass | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	251,963	238,612
Grades 4 and 5 – pass | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	159,833	126,308
Grades 4 and 5 – pass | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	49,461	50,234
Grades 4 and 5 – pass | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	498,392	456,911
Grade 6 – special mention | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	1,945	919
Grade 6 – special mention | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	7,418	1,608
Grade 6 – special mention | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	998	998
Grade 6 – special mention | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	1,441	1,279
Grade 6 – special mention | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	11,802	4,804
Grade 7 – substandard | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	524	2,324
Grade 7 – substandard | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	1,143	1,176
Grade 7 – substandard | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	11,058	11,478
Grade 7 – substandard | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	655	684
Grade 7 – substandard | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	13,380	15,662
Grade 8 – doubtful | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 8 – doubtful | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 8 – doubtful | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 8 – doubtful | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Grade 8 – doubtful | Commercial, Construction and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Not graded | Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	32,738	33,059
Not graded | Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	98	155
Not graded | Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	61,974	68,752
Not graded | Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	94,810	101,966
Pass | Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	12,453	12,542
Pass | Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	16	18
Pass | Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	388	740
Pass | Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	12,857	13,300
Special mention | Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	354	88
Special mention | Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Special mention | Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	386
Special mention | Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	354	474
Substandard | Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	177	192
Substandard | Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Substandard | Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	53	0
Substandard | Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	230	192
Doubtful | Commercial Real Estate | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Doubtful | Commercial Real Estate | Home improvement and home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Doubtful | Installment and student loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	0	0
Doubtful | Real Estate and Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans outstanding	$ 0	$ 0
Minimum | Grades 4 and 5 – pass
Financing Receivable, Credit Quality Indicator [Line Items]
Notes receivable, period of loss recognition	3 years
Maximum | Grades 4 and 5 – pass
Financing Receivable, Credit Quality Indicator [Line Items]
Notes receivable, period of loss recognition	4 years