Loans, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	$ 2,663,808	$ 2,639,104	$ 2,643,065
Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	70,080	68,021
Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	307,851	311,157
Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,745,418	1,728,780
Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	428,847	420,993
Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	66,803	66,810
Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	44,809	43,343
Agricultural [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	96,811	91,317	93,573
Agricultural [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,710	3,594
Agricultural [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	14,405	12,380
Agricultural [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	45,924	43,308
Agricultural [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	26,066	24,857
Agricultural [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,606	3,110
Agricultural [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,100	4,068
Commercial and Financial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	228,074	221,323	227,403
Commercial and Financial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,517	3,461
Commercial and Financial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	46,648	47,843
Commercial and Financial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	122,917	117,114
Commercial and Financial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	44,584	44,543
Commercial and Financial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	6,438	5,157
Commercial and Financial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,970	3,205
Real Estate: Construction, 1 to 4 family residential [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	83,445	80,209
Real Estate: Construction, 1 to 4 family residential [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	260
Real Estate: Construction, 1 to 4 family residential [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	9,646	8,868
Real Estate: Construction, 1 to 4 family residential [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	53,520	51,093
Real Estate: Construction, 1 to 4 family residential [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	18,506	17,505
Real Estate: Construction, 1 to 4 family residential [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	747	2,483
Real Estate: Construction, 1 to 4 family residential [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,026	0
Real Estate: Construction, land development and commercial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	102,820	108,410
Real Estate: Construction, land development and commercial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	241	190
Real Estate: Construction, land development and commercial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	15,969	23,217
Real Estate: Construction, land development and commercial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	48,413	47,987
Real Estate: Construction, land development and commercial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	30,190	29,009
Real Estate: Construction, land development and commercial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	7,218	7,428
Real Estate: Construction, land development and commercial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	789	579
Real Estate: Mortgage, farmland [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	246,203	242,730	$ 238,109
Real Estate: Mortgage, farmland [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	6,837	3,630
Real Estate: Mortgage, farmland [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	37,941	40,118
Real Estate: Mortgage, farmland [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	136,433	134,738
Real Estate: Mortgage, farmland [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	53,050	53,147
Real Estate: Mortgage, farmland [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,971	3,033
Real Estate: Mortgage, farmland [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	7,971	8,064
Real Estate: Mortgage, 1 to 4 family first liens [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	905,951	910,742
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	2,732	3,209
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	32,019	32,474
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	742,836	751,215
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	101,037	96,353
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	10,534	11,167
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	16,793	16,324
Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	148,444	149,227
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	262	261
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	4,086	4,233
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	135,444	136,079
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	5,494	5,473
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,341	1,469
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,817	1,712
Real Estate: Mortgage, multi-family [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	357,194	350,761
Real Estate: Mortgage, multi-family [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	18,974	18,955
Real Estate: Mortgage, multi-family [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	51,338	47,871
Real Estate: Mortgage, multi-family [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	191,849	189,391
Real Estate: Mortgage, multi-family [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	61,677	60,965
Real Estate: Mortgage, multi-family [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	27,361	27,559
Real Estate: Mortgage, multi-family [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	5,995	6,020
Real Estate: Mortgage, commercial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	410,200	402,181
Real Estate: Mortgage, commercial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	26,494	27,017
Real Estate: Mortgage, commercial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	81,334	79,467
Real Estate: Mortgage, commercial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	214,053	206,196
Real Estate: Mortgage, commercial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	80,061	81,381
Real Estate: Mortgage, commercial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	4,967	4,802
Real Estate: Mortgage, commercial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,291	3,318
Loans to individuals [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	31,749	32,308
Loans to individuals [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	0
Loans to individuals [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	199	221
Loans to individuals [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	30,871	31,385
Loans to individuals [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	387	437
Loans to individuals [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	235	212
Loans to individuals [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	57	53
Obligations of state and political subdivisions [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	52,917	49,896
Obligations of state and political subdivisions [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	7,313	7,444
Obligations of state and political subdivisions [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	14,266	14,465
Obligations of state and political subdivisions [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	23,158	20,274
Obligations of state and political subdivisions [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	7,795	7,323
Obligations of state and political subdivisions [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	385	390
Obligations of state and political subdivisions [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	$ 0	$ 0