Loans - Credit Risk Rating for Commercial, Construction and Non-Consumer Related Loans (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) rating	Dec. 31, 2018 USD ($)
Receivables [Abstract]
Number of risk rating approaches | rating	2
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	$ 120,735	$ 131,563
Credit risk ratings for consumer related loans and other homogeneous loans	120,735	131,563
Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	449,393	456,370
Credit risk ratings for consumer related loans and other homogeneous loans	449,393	456,370
Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	48,137	56,978
Credit risk ratings for consumer related loans and other homogeneous loans	48,137	56,978
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	224,713	229,448
Credit risk ratings for consumer related loans and other homogeneous loans	224,713	229,448
Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	116,443	108,795
Credit risk ratings for consumer related loans and other homogeneous loans	116,443	108,795
Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	60,100	61,149
Credit risk ratings for consumer related loans and other homogeneous loans	60,100	61,149
Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	51,062	59,431
Credit risk ratings for consumer related loans and other homogeneous loans	51,062	59,431
Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	184	321
Credit risk ratings for consumer related loans and other homogeneous loans	184	321
Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	69,489	71,811
Credit risk ratings for consumer related loans and other homogeneous loans	69,489	71,811
Grades 1 and 2 | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	3,135	3,285
Credit risk ratings for consumer related loans and other homogeneous loans	3,135	3,285
Grades 1 and 2 | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	310	324
Credit risk ratings for consumer related loans and other homogeneous loans	310	324
Grades 1 and 2 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	2,825	2,881
Credit risk ratings for consumer related loans and other homogeneous loans	2,825	2,881
Grades 1 and 2 | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grades 1 and 2 | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	80
Credit risk ratings for consumer related loans and other homogeneous loans	0	80
Grade 3 | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	989	1,028
Credit risk ratings for consumer related loans and other homogeneous loans	989	1,028
Grade 3 | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 3 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	989	1,028
Credit risk ratings for consumer related loans and other homogeneous loans	989	1,028
Grade 3 | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 3 | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grades 4 and 5 – pass | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	424,270	434,201
Credit risk ratings for consumer related loans and other homogeneous loans	424,270	434,201
Grades 4 and 5 – pass | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	44,276	53,843
Credit risk ratings for consumer related loans and other homogeneous loans	44,276	53,843
Grades 4 and 5 – pass | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	217,044	222,970
Credit risk ratings for consumer related loans and other homogeneous loans	217,044	222,970
Grades 4 and 5 – pass | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	104,914	97,132
Credit risk ratings for consumer related loans and other homogeneous loans	104,914	97,132
Grades 4 and 5 – pass | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	58,036	60,256
Credit risk ratings for consumer related loans and other homogeneous loans	58,036	60,256
Grade 6 – special mention | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	4,049	2,228
Credit risk ratings for consumer related loans and other homogeneous loans	4,049	2,228
Grade 6 – special mention | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	1,051	48
Credit risk ratings for consumer related loans and other homogeneous loans	1,051	48
Grade 6 – special mention | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	1,661	2,180
Credit risk ratings for consumer related loans and other homogeneous loans	1,661	2,180
Grade 6 – special mention | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 6 – special mention | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	1,337	0
Credit risk ratings for consumer related loans and other homogeneous loans	1,337	0
Grade 7 – substandard | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	16,950	15,628
Credit risk ratings for consumer related loans and other homogeneous loans	16,950	15,628
Grade 7 – substandard | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	2,500	2,763
Credit risk ratings for consumer related loans and other homogeneous loans	2,500	2,763
Grade 7 – substandard | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	2,194	389
Credit risk ratings for consumer related loans and other homogeneous loans	2,194	389
Grade 7 – substandard | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	11,529	11,663
Credit risk ratings for consumer related loans and other homogeneous loans	11,529	11,663
Grade 7 – substandard | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	727	813
Credit risk ratings for consumer related loans and other homogeneous loans	727	813
Grade 8 – doubtful | Commercial Risk, Construction, and Other Non-Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 8 – doubtful | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 8 – doubtful | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 8 – doubtful | Real Estate Construction and Development
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Grade 8 – doubtful | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Not graded
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	106,344	120,853
Credit risk ratings for consumer related loans and other homogeneous loans	106,344	120,853
Not graded | Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	37,800	49,563
Credit risk ratings for consumer related loans and other homogeneous loans	37,800	49,563
Not graded | Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	165	300
Credit risk ratings for consumer related loans and other homogeneous loans	165	300
Not graded | Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	68,379	70,990
Credit risk ratings for consumer related loans and other homogeneous loans	68,379	70,990
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	13,289	9,987
Credit risk ratings for consumer related loans and other homogeneous loans	13,289	9,987
Pass | Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	12,486	9,186
Credit risk ratings for consumer related loans and other homogeneous loans	12,486	9,186
Pass | Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	19	21
Credit risk ratings for consumer related loans and other homogeneous loans	19	21
Pass | Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	784	780
Credit risk ratings for consumer related loans and other homogeneous loans	784	780
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	905	470
Credit risk ratings for consumer related loans and other homogeneous loans	905	470
Special mention | Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	579	470
Credit risk ratings for consumer related loans and other homogeneous loans	579	470
Special mention | Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Special mention | Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	326	0
Credit risk ratings for consumer related loans and other homogeneous loans	326	0
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	197	253
Credit risk ratings for consumer related loans and other homogeneous loans	197	253
Substandard | Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	197	212
Credit risk ratings for consumer related loans and other homogeneous loans	197	212
Substandard | Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Substandard | Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	41
Credit risk ratings for consumer related loans and other homogeneous loans	0	41
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Doubtful | Residential Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Doubtful | Home Improvement and Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	0	0
Doubtful | Installment and Student Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Credit risk ratings for commercial, construction, and other non-consumer related loans	0	0
Credit risk ratings for consumer related loans and other homogeneous loans	$ 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