Loans - Impaired Financing Receivables Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Recorded Investment
With no related allowance recorded	$ 15,201	$ 14,356	$ 12,563
With a related allowance recorded	12,784	17,131	21,101
Total	27,985	31,487	33,664
Unpaid Principal Balance
With no related allowance recorded	19,515	18,735	16,365
With a related allowance recorded	13,023	17,202	21,377
Total	32,538	35,937	37,742
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	2,114	2,166	2,343
Total	2,114	2,166	2,343
Average Recorded Investment
With no related allowance recorded	15,090	15,306	13,425
With an related allowance recorded	13,005	17,810	21,163
Total	28,095	33,116	34,588
Interest Income Recognized
With no related allowance recorded	266	270	195
With an related allowance recorded	527	802	880
Total	793	1,072	1,075
Agricultural [Member]
Recorded Investment
With no related allowance recorded	1,395	1,822	800
With a related allowance recorded	1,065	3,094	10,920
Total	2,460	4,916	11,720
Unpaid Principal Balance
With no related allowance recorded	1,663	2,193	971
With a related allowance recorded	1,229	3,149	10,978
Total	2,892	5,342	11,949
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	479	133	856
Total	479	133	856
Average Recorded Investment
With no related allowance recorded	1,071	2,044	923
With an related allowance recorded	980	3,526	11,258
Total	2,051	5,570	12,181
Interest Income Recognized
With no related allowance recorded	23	19	0
With an related allowance recorded	7	160	464
Total	30	179	464
Commercial and financial [Member]
Recorded Investment
With no related allowance recorded	1,650	1,725	1,540
With a related allowance recorded	2,512	1,043	937
Total	4,162	2,768	2,477
Unpaid Principal Balance
With no related allowance recorded	2,503	2,487	2,175
With a related allowance recorded	2,512	1,043	955
Total	5,015	3,530	3,130
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	1,189	1,018	718
Total	1,189	1,018	718
Average Recorded Investment
With no related allowance recorded	1,977	2,080	1,662
With an related allowance recorded	2,793	1,249	777
Total	4,770	3,329	2,439
Interest Income Recognized
With no related allowance recorded	58	51	18
With an related allowance recorded	107	60	27
Total	165	111	45
Construction, 1 to 4 family residential [Member]
Recorded Investment
With no related allowance recorded	111	114	117
With a related allowance recorded	698	0	815
Total	809	114	932
Unpaid Principal Balance
With no related allowance recorded	148	150	151
With a related allowance recorded	698	0	815
Total	846	150	966
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	4	0	105
Total	4	0	105
Average Recorded Investment
With no related allowance recorded	113	116	131
With an related allowance recorded	622	0	537
Total	735	116	668
Interest Income Recognized
With no related allowance recorded	0	5	6
With an related allowance recorded	28	0	27
Total	28	5	33
Construction, land development and commercial [Member]
Recorded Investment
With no related allowance recorded	328	338	204
With a related allowance recorded	0	505	0
Total	328	843	204
Unpaid Principal Balance
With no related allowance recorded	344	371	290
With a related allowance recorded	0	505	0
Total	344	876	290
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	0	39	0
Total	0	39	0
Average Recorded Investment
With no related allowance recorded	333	344	207
With an related allowance recorded	0	321	0
Total	333	665	207
Interest Income Recognized
With no related allowance recorded	18	14	5
With an related allowance recorded	0	14	0
Total	18	28	5
Mortgage, farmland [Member]
Recorded Investment
With no related allowance recorded	3,612	2,523	2,594
With a related allowance recorded	0	5,439	5,434
Total	3,612	7,962	8,028
Unpaid Principal Balance
With no related allowance recorded	4,071	2,902	2,887
With a related allowance recorded	0	5,439	5,434
Total	4,071	8,341	8,321
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	0	238	390
Total	0	238	390
Average Recorded Investment
With no related allowance recorded	3,068	2,476	2,767
With an related allowance recorded	0	5,596	5,591
Total	3,068	8,072	8,358
Interest Income Recognized
With no related allowance recorded	89	56	67
With an related allowance recorded	0	242	240
Total	89	298	307
Mortgage, 1 to 4 family first liens [Member]
Recorded Investment
With no related allowance recorded	6,089	6,045	5,011
With a related allowance recorded	899	577	1,266
Total	6,988	6,622	6,277
Unpaid Principal Balance
With no related allowance recorded	7,819	7,507	6,137
With a related allowance recorded	974	593	1,374
Total	8,793	8,100	7,511
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	70	63	79
Total	70	63	79
Average Recorded Investment
With no related allowance recorded	6,435	6,286	5,265
With an related allowance recorded	888	585	1,226
Total	7,323	6,871	6,491
Interest Income Recognized
With no related allowance recorded	36	80	53
With an related allowance recorded	25	20	43
Total	61	100	96
Mortgage, 1 to 4 family junior liens [Member]
Recorded Investment
With no related allowance recorded	0	7	153
With a related allowance recorded	24	25	612
Total	24	32	765
Unpaid Principal Balance
With no related allowance recorded	254	482	646
With a related allowance recorded	24	25	667
Total	278	507	1,313
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	2	3	11
Total	2	3	11
Average Recorded Investment
With no related allowance recorded	0	23	186
With an related allowance recorded	25	26	637
Total	25	49	823
Interest Income Recognized
With no related allowance recorded	0	0	0
With an related allowance recorded	1	1	27
Total	1	1	27
Mortgage, multi-family [Member]
Recorded Investment
With no related allowance recorded	145	218	243
With a related allowance recorded	7,447	6,179	0
Total	7,592	6,397	243
Unpaid Principal Balance
With no related allowance recorded	213	355	362
With a related allowance recorded	7,447	6,179	0
Total	7,660	6,534	362
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	305	480	0
Total	305	480	0
Average Recorded Investment
With no related allowance recorded	153	231	288
With an related allowance recorded	7,543	6,247	0
Total	7,696	6,478	288
Interest Income Recognized
With no related allowance recorded	0	0	0
With an related allowance recorded	346	281	0
Total	346	281	0
Real Estate: Mortgage, commercial [Member]
Recorded Investment
With no related allowance recorded	1,871	1,564	1,901
With a related allowance recorded	75	79	967
Total	1,946	1,643	2,868
Unpaid Principal Balance
With no related allowance recorded	2,486	2,274	2,727
With a related allowance recorded	75	79	1,004
Total	2,561	2,353	3,731
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	1	2	34
Total	1	2	34
Average Recorded Investment
With no related allowance recorded	1,940	1,706	1,996
With an related allowance recorded	77	81	986
Total	2,017	1,787	2,982
Interest Income Recognized
With no related allowance recorded	42	45	46
With an related allowance recorded	4	4	36
Total	46	49	82
Loans to individuals [Member]
Recorded Investment
With no related allowance recorded	0	0	0
With a related allowance recorded	64	190	150
Total	64	190	150
Unpaid Principal Balance
With no related allowance recorded	14	14	19
With a related allowance recorded	64	190	150
Total	78	204	169
Related Allowance
With no related allowance recorded	0	0	0
With an related allowance recorded	64	190	150
Total	64	190	150
Average Recorded Investment
With no related allowance recorded	0	0	0
With an related allowance recorded	77	179	151
Total	77	179	151
Interest Income Recognized
With no related allowance recorded	0	0	0
With an related allowance recorded	9	20	16
Total	$ 9	$ 20	$ 16