Note 4 - Loans Receivable - Delinquencies Within the Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Past due	$ 2,490	$ 3,509
Non-accrual Loans	3,711	2,290
Current Loans	748,524	612,232
Loans receivable	754,725	618,031	$ 597,721
Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	2,490	2,032
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	1,477
Residential Portfolio Segment [Member]
Loans receivable	143,067	144,107	144,972
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Past due	264	511
Non-accrual Loans	458	253
Current Loans	109,569	116,175
Loans receivable	110,291	116,939
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	264	381
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	130
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Past due	0	118
Non-accrual Loans	337	634
Current Loans	32,439	26,416
Loans receivable	32,776	27,168
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	0	118
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	416,157	328,438	303,660
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Past due	838	2,322
Non-accrual Loans	894	432
Current Loans	316,097	254,030
Loans receivable	317,829	256,784
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	838	975
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	1,347
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Past due	191	9
Non-accrual Loans	0	13
Current Loans	51,456	41,717
Loans receivable	51,647	41,739
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	191	9
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Past due	243	0
Non-accrual Loans	476	0
Current Loans	45,962	29,915
Loans receivable	46,681	29,915
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	243	0
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Home Equity Portfolio Segment [Member]
Past due	467	39
Non-accrual Loans	99	491
Current Loans	55,971	51,629
Loans receivable	56,537	52,159	53,342
Home Equity Portfolio Segment [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	467	39
Home Equity Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Consumer Portfolio Segment [Member]
Past due	121	135
Non-accrual Loans	142	127
Current Loans	18,749	16,303
Loans receivable	19,012	16,565	16,491
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	121	135
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Portfolio Segment [Member]
Loans receivable	119,952	76,762	$ 79,256
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Past due	346	284
Non-accrual Loans	794	308
Current Loans	71,919	58,461
Loans receivable	73,059	59,053
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	346	284
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Past due	20	91
Non-accrual Loans	511	32
Current Loans	46,362	17,586
Loans receivable	46,893	17,709
Commercial Portfolio Segment [Member] | Agricultural Loan [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Past due	20	91
Commercial Portfolio Segment [Member] | Agricultural Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	$ 0	$ 0