Note 3 - Loans and Allowance for Loan Losses - Loans by Aging (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Loans receivable, past due	$ 5,769,000	$ 1,596,000
Loans receivable, current	631,606,000	542,802,000
Loans receivable	637,375,018	544,398,300
Loans receivable, past due and accruing
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	3,736,000	965,000
Loans receivable, current	102,565,000	105,446,000
Loans receivable	106,300,790	106,410,559
Loans receivable, past due and accruing
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	775,000
Loans receivable, current	84,450,000	48,483,000
Loans receivable	85,225,074	48,483,523
Loans receivable, past due and accruing
Real Estate, Construction [Member]
Loans receivable, past due
Loans receivable, current	64,744,000	40,912,000
Loans receivable	64,743,582	40,912,307
Loans receivable, past due and accruing
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	378,000
Loans receivable, current	261,488,000	249,581,000
Loans receivable	261,866,285	249,580,873
Loans receivable, past due and accruing
Commercial Portfolio Segment [Member]
Loans receivable, past due	864,000	593,000
Loans receivable, current	93,659,000	74,812,000
Loans receivable	94,522,840	75,404,732
Loans receivable, past due and accruing
Consumer and Other Loans [Member]
Loans receivable, past due	16,000	38,000
Loans receivable, current	24,700,000	23,568,000
Loans receivable	24,716,447	23,606,306
Loans receivable, past due and accruing
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, past due	1,812,000	367,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	510,000	367,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	775,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	243,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	276,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	8,000
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, past due	874,000	495,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	731,000	495,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	135,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	8,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	3,083,000	734,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	2,495,000	103,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	588,000	593,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due		$ 38,000