Note 3 - Loans Receivable - Internal Classification of the Loan Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Loans receivable	$ 582,757	$ 514,247	$ 509,140
Performing Financial Instruments [Member]
Loans receivable	581,098	513,270
Restructured Loans [Member]
Loans receivable
Nonperforming Financial Instruments [Member]
Loans receivable	1,659	977
Residential Portfolio Segment [Member]
Loans receivable	143,323	135,217	140,346
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	112,314	109,911
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member] | Performing Financial Instruments [Member]
Loans receivable	111,948	109,436
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member] | Restructured Loans [Member]
Loans receivable
Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	366	475
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	31,009	25,306
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member] | Performing Financial Instruments [Member]
Loans receivable	30,672	25,306
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member] | Restructured Loans [Member]
Loans receivable
Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	337
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	281,525	244,783	246,005
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	216,264	194,805
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans receivable	215,737	194,805
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member] | Restructured Loans [Member]
Loans receivable
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	527
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	36,581	38,351
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Performing Financial Instruments [Member]
Loans receivable	36,581	38,351
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Restructured Loans [Member]
Loans receivable
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Nonperforming Financial Instruments [Member]
Loans receivable
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	28,680	11,627
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member] | Performing Financial Instruments [Member]
Loans receivable	28,680	11,627
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member] | Restructured Loans [Member]
Loans receivable
Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member] | Nonperforming Financial Instruments [Member]
Loans receivable
Home Equity Portfolio Segment [Member]
Loans receivable	53,178	52,672	49,266
Home Equity Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans receivable	52,971	52,430
Home Equity Portfolio Segment [Member] | Restructured Loans [Member]
Loans receivable
Home Equity Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	207	242
Consumer Portfolio Segment [Member]
Loans receivable	16,635	15,712	15,293
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans receivable	16,534	15,559
Consumer Portfolio Segment [Member] | Restructured Loans [Member]
Loans receivable
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	101	153
Commercial Portfolio Segment [Member]
Loans receivable	88,096	65,863	$ 58,230
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	69,951	63,300
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Performing Financial Instruments [Member]
Loans receivable	69,830	63,193
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Restructured Loans [Member]
Loans receivable
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Nonperforming Financial Instruments [Member]
Loans receivable	121	107
Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	18,145	2,563
Commercial Portfolio Segment [Member] | Agricultural Loan [Member] | Performing Financial Instruments [Member]
Loans receivable	18,145	2,563
Commercial Portfolio Segment [Member] | Agricultural Loan [Member] | Restructured Loans [Member]
Loans receivable
Commercial Portfolio Segment [Member] | Agricultural Loan [Member] | Nonperforming Financial Instruments [Member]
Loans receivable
Pass [Member]
Loans receivable	577,978	512,204
Pass [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	111,190	109,167
Pass [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	30,672	24,850
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	213,816	194,502
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	36,581	38,351
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	28,680	11,627
Pass [Member] | Home Equity Portfolio Segment [Member]
Loans receivable	52,971	52,430
Pass [Member] | Consumer Portfolio Segment [Member]
Loans receivable	16,484	15,549
Pass [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	69,837	63,165
Pass [Member] | Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	17,747	2,563
Special Mention [Member]
Loans receivable	0	0
Special Mention [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	0	0
Special Mention [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	0	0
Special Mention [Member] | Home Equity Portfolio Segment [Member]
Loans receivable	0	0
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	0	0
Substandard [Member]
Loans receivable	4,779	1,994
Substandard [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	1,124	744
Substandard [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	337	456
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	2,448	303
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	0	0
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	0	0
Substandard [Member] | Home Equity Portfolio Segment [Member]
Loans receivable	207	242
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans receivable	151	136
Substandard [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	114	113
Substandard [Member] | Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	398	0
Doubtful [Member]
Loans receivable	0	0
Doubtful [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	0	0
Doubtful [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	0	0
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	0	0
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	0	0
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	0	0
Doubtful [Member] | Home Equity Portfolio Segment [Member]
Loans receivable	0	0
Doubtful [Member] | Consumer Portfolio Segment [Member]
Loans receivable	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member]
Loans receivable		49
Unlikely to be Collected Financing Receivable [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Loans [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Residential Portfolio Segment [Member] | One-to-Four Family Construction [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Loan [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loan [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Home Equity Portfolio Segment [Member]
Loans receivable	0	0
Unlikely to be Collected Financing Receivable [Member] | Consumer Portfolio Segment [Member]
Loans receivable	0	27
Unlikely to be Collected Financing Receivable [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans receivable	0	22
Unlikely to be Collected Financing Receivable [Member] | Commercial Portfolio Segment [Member] | Agricultural Loan [Member]
Loans receivable	$ 0	$ 0