Loans and Allowance for Loan Losses - Schedule of Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unpaid contractual principal	$ 10,641	$ 11,710	$ 8,755
Impaired loan balance	8,691	9,760	6,728
Impaired loans without an allowance	5,994	5,551	5,368
Impaired loans with an allowance	2,697	4,209	1,360
Related allowance recorded	310	642	274
Year-to-date average loan balance	9,745	10,017	7,374
Year-to-date interest income recognized	603	569	601
One-to-Four Family Residential Real Estate Loans [Member]
Unpaid contractual principal	623	747	780
Impaired loan balance	623	747	780
Impaired loans without an allowance	413	503	780
Impaired loans with an allowance	210	244
Related allowance recorded	100	73
Year-to-date average loan balance	640	774	798
Year-to-date interest income recognized	10	8	7
Construction and Land Loan [Member]
Unpaid contractual principal	3,543	3,766	3,672
Impaired loan balance	1,808	2,031	1,937
Impaired loans without an allowance	1,383	430	1,937
Impaired loans with an allowance	425	1,601
Related allowance recorded	103	102
Year-to-date average loan balance	2,689	2,033	2,068
Year-to-date interest income recognized	53	65	72
Commercial Real Estate Loans [Member]
Unpaid contractual principal	3,912	3,973	2,445
Impaired loan balance	3,912	3,973	2,445
Impaired loans without an allowance	2,120	3,888	2,145
Impaired loans with an allowance	1,792	85	300
Related allowance recorded	67	52	81
Year-to-date average loan balance	3,928	3,989	2,587
Year-to-date interest income recognized	487	490	505
Commercial Loans [Member]
Unpaid contractual principal	1,528	2,002	355
Impaired loan balance	1,528	2,002	355
Impaired loans without an allowance	1,446	11	46
Impaired loans with an allowance	82	1,991	309
Related allowance recorded	27	391	87
Year-to-date average loan balance	1,537	2,082	425
Year-to-date interest income recognized			2
Agriculture Loans [Member]
Unpaid contractual principal	932	1,048	1,173
Impaired loan balance	717	833	881
Impaired loans without an allowance	529	545	147
Impaired loans with an allowance	188	288	734
Related allowance recorded	13	24	89
Year-to-date average loan balance	844	912	1,000
Year-to-date interest income recognized	52	1	2
Municipal Loans [Member]
Unpaid contractual principal	58	140	258
Impaired loan balance	58	140	258
Impaired loans without an allowance	58	140	258
Impaired loans with an allowance
Related allowance recorded
Year-to-date average loan balance	58	192	418
Year-to-date interest income recognized	1	5
Consumer Loans [Member]
Unpaid contractual principal	45	34	72
Impaired loan balance	45	34	72
Impaired loans without an allowance	45	34	55
Impaired loans with an allowance			17
Related allowance recorded			17
Year-to-date average loan balance	49	35	78
Year-to-date interest income recognized			$ 13