Note 5 - Loans and Allowance for Loan Losses - Loans by Aging (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Loans receivable, past due	$ 11,294,000	$ 5,769,000
Loans receivable, current	769,522,000	631,606,000
Loans receivable	780,816,020	637,375,018
Loans receivable, past due and accruing
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	2,555,000	3,736,000
Loans receivable, current	132,884,000	102,565,000
Loans receivable	135,439,026	106,300,790
Loans receivable, past due and accruing
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	6,015,000	775,000
Loans receivable, current	77,189,000	84,450,000
Loans receivable	83,204,490	85,225,074
Loans receivable, past due and accruing
Real Estate, Construction [Member]
Loans receivable, past due	517,000
Loans receivable, current	105,458,000	64,744,000
Loans receivable	105,974,945	64,743,582
Loans receivable, past due and accruing
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	533,000	378,000
Loans receivable, current	299,793,000	261,488,000
Loans receivable	300,325,513	261,866,285
Loans receivable, past due and accruing
Commercial Portfolio Segment [Member]
Loans receivable, past due	1,546,000	864,000
Loans receivable, current	118,746,000	93,659,000
Loans receivable	120,292,323	94,522,840
Loans receivable, past due and accruing
Consumer and Other Loans [Member]
Loans receivable, past due	128,000	16,000
Loans receivable, current	35,452,000	24,700,000
Loans receivable	35,579,723	24,716,447
Loans receivable, past due and accruing
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, past due	7,457,000	1,812,000
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	191,000	510,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	6,015,000	775,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due	517,000
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	687,000	276,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	47,000	8,000
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, past due	844,000	874,000
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	184,000	731,000
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	533,000	135,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	96,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	31,000	8,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, past due	2,993,000	3,083,000
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	2,180,000	2,495,000
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	763,000	588,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	$ 50,000