Loans, Past Due Receivables (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of accruing loans past due 90 days or more	3	8
Schedule of past due loans [Abstract]
Total Past Due	$ 11,299	$ 12,963
Current	2,544,483	2,446,708
Total Loans Receivable	2,555,782	2,459,671	$ 2,419,894
Accruing Loans Past Due 90 Days or More	338	971
Agricultural [Member]
Schedule of past due loans [Abstract]
Total Past Due	716	593
Current	78,439	87,987
Total Loans Receivable	79,155	88,580	76,484
Accruing Loans Past Due 90 Days or More	0	0
Commercial and Financial [Member]
Schedule of past due loans [Abstract]
Total Past Due	1,536	560
Current	213,145	218,072
Total Loans Receivable	214,681	218,632	214,199
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Construction, 1 to 4 family residential [Member]
Schedule of past due loans [Abstract]
Total Past Due	1,003	0
Current	64,929	69,738
Total Loans Receivable	65,932	69,738
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Construction, land development and commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	458	246
Current	105,554	109,349
Total Loans Receivable	106,012	109,595
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Mortgage, farmland [Member]
Schedule of past due loans [Abstract]
Total Past Due	991	269
Current	229,041	215,017
Total Loans Receivable	230,032	215,286	$ 208,982
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Mortgage, 1 to 4 family first liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	5,609	9,832
Current	894,328	821,759
Total Loans Receivable	899,937	831,591
Accruing Loans Past Due 90 Days or More	338	971
Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	147	695
Current	149,165	143,505
Total Loans Receivable	149,312	144,200
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Mortgage, multi-family [Member]
Schedule of past due loans [Abstract]
Total Past Due	152	0
Current	347,508	336,810
Total Loans Receivable	347,660	336,810
Accruing Loans Past Due 90 Days or More	0	0
Real Estate: Mortgage, commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	484	501
Current	381,482	360,695
Total Loans Receivable	381,966	361,196
Accruing Loans Past Due 90 Days or More	0	0
Loans to individuals [Member]
Schedule of past due loans [Abstract]
Total Past Due	203	267
Current	27,743	26,150
Total Loans Receivable	27,946	26,417
Accruing Loans Past Due 90 Days or More	0	0
State and political subdivisions [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
Current	53,149	57,626
Total Loans Receivable	53,149	57,626
Accruing Loans Past Due 90 Days or More	0	0
30 - 59 Days Past Due [Member]
Schedule of past due loans [Abstract]
Total Past Due	3,852	7,521
30 - 59 Days Past Due [Member] | Agricultural [Member]
Schedule of past due loans [Abstract]
Total Past Due	474	324
30 - 59 Days Past Due [Member] | Commercial and Financial [Member]
Schedule of past due loans [Abstract]
Total Past Due	991	447
30 - 59 Days Past Due [Member] | Real Estate: Construction, 1 to 4 family residential [Member]
Schedule of past due loans [Abstract]
Total Past Due	566	0
30 - 59 Days Past Due [Member] | Real Estate: Construction, land development and commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	458	246
30 - 59 Days Past Due [Member] | Real Estate: Mortgage, farmland [Member]
Schedule of past due loans [Abstract]
Total Past Due	240	269
30 - 59 Days Past Due [Member] | Real Estate: Mortgage, 1 to 4 family first liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	780	5,143
30 - 59 Days Past Due [Member] | Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	59	579
30 - 59 Days Past Due [Member] | Real Estate: Mortgage, multi-family [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
30 - 59 Days Past Due [Member] | Real Estate: Mortgage, commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	135	307
30 - 59 Days Past Due [Member] | Loans to individuals [Member]
Schedule of past due loans [Abstract]
Total Past Due	149	206
30 - 59 Days Past Due [Member] | State and political subdivisions [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
60 - 89 Days Past Due [Member]
Schedule of past due loans [Abstract]
Total Past Due	4,684	2,119
60 - 89 Days Past Due [Member] | Agricultural [Member]
Schedule of past due loans [Abstract]
Total Past Due	84	0
60 - 89 Days Past Due [Member] | Commercial and Financial [Member]
Schedule of past due loans [Abstract]
Total Past Due	545	20
60 - 89 Days Past Due [Member] | Real Estate: Construction, 1 to 4 family residential [Member]
Schedule of past due loans [Abstract]
Total Past Due	437	0
60 - 89 Days Past Due [Member] | Real Estate: Construction, land development and commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
60 - 89 Days Past Due [Member] | Real Estate: Mortgage, farmland [Member]
Schedule of past due loans [Abstract]
Total Past Due	751	0
60 - 89 Days Past Due [Member] | Real Estate: Mortgage, 1 to 4 family first liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	2,225	1,750
60 - 89 Days Past Due [Member] | Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	88	116
60 - 89 Days Past Due [Member] | Real Estate: Mortgage, multi-family [Member]
Schedule of past due loans [Abstract]
Total Past Due	152	0
60 - 89 Days Past Due [Member] | Real Estate: Mortgage, commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	349	178
60 - 89 Days Past Due [Member] | Loans to individuals [Member]
Schedule of past due loans [Abstract]
Total Past Due	53	55
60 - 89 Days Past Due [Member] | State and political subdivisions [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member]
Schedule of past due loans [Abstract]
Total Past Due	2,763	3,323
90 Days or More Past Due [Member] | Agricultural [Member]
Schedule of past due loans [Abstract]
Total Past Due	158	269
90 Days or More Past Due [Member] | Commercial and Financial [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	93
90 Days or More Past Due [Member] | Real Estate: Construction, 1 to 4 family residential [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member] | Real Estate: Construction, land development and commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member] | Real Estate: Mortgage, farmland [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member] | Real Estate: Mortgage, 1 to 4 family first liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	2,604	2,939
90 Days or More Past Due [Member] | Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member] | Real Estate: Mortgage, multi-family [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	0
90 Days or More Past Due [Member] | Real Estate: Mortgage, commercial [Member]
Schedule of past due loans [Abstract]
Total Past Due	0	16
90 Days or More Past Due [Member] | Loans to individuals [Member]
Schedule of past due loans [Abstract]
Total Past Due	1	6
90 Days or More Past Due [Member] | State and political subdivisions [Member]
Schedule of past due loans [Abstract]
Total Past Due	$ 0	$ 0