Note 8 - Fair Value - Carrying Amount and Fair Value of Financial Instruments Included in the Consolidated Balance Sheet (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Financial Assets:
Securities-available for sale	$ 97,509,000	$ 99,350,000
Securities-equities	473,000	1,817,000
Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Securities-available for sale	4,395,000	4,472,000
Securities-equities	473,000	1,683,000
Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Securities-available for sale	89,614,000	86,880,000
Securities-equities
Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Securities-available for sale	3,500,000	7,998,000
Securities-equities		134,000
Reported Value Measurement [Member]
Financial Assets:
Cash and cash equivalents	22,680,000	14,374,000
Securities-available for sale	97,509,000	99,350,000
Securities-equities	473,000	1,817,000
Loans held for sale	120,000	504,000
Loans, net	592,125,000	577,234,000
Federal bank stock	4,466,000	4,662,000
Accrued interest receivable	2,302,000	2,217,000
Total	719,675,000	700,158,000
Accrued interest receivable	2,302,000	2,217,000
Total	719,675,000	700,158,000
Financial Liabilities:
Deposits	682,361,000	654,643,000
Borrowed funds	19,800,000	26,000,000
Accrued interest payable	460,000	413,000
Total	702,621,000	681,056,000
Borrowed funds	19,800,000	26,000,000
Estimate of Fair Value Measurement [Member]
Financial Assets:
Cash and cash equivalents	22,680,000	14,374,000
Securities-available for sale	97,509,000	99,350,000
Securities-equities	473,000	1,817,000
Loans held for sale	120,000	504,000
Loans, net	583,741,000	577,616,000
Federal bank stock
Accrued interest receivable	2,302,000	2,217,000
Total	706,825,000	695,878,000
Accrued interest receivable	2,302,000	2,217,000
Total	706,825,000	695,878,000
Financial Liabilities:
Deposits	685,333,000	657,414,000
Borrowed funds	19,414,000	25,499,000
Accrued interest payable	460,000	413,000
Total	705,207,000	683,326,000
Borrowed funds	19,414,000	25,499,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	22,680,000	14,374,000
Securities-available for sale	4,395,000	4,472,000
Securities-equities	473,000	1,683,000
Loans held for sale
Loans, net
Federal bank stock
Accrued interest receivable	88,000	59,000
Total	27,636,000	20,588,000
Accrued interest receivable	88,000	59,000
Total	27,636,000	20,588,000
Financial Liabilities:
Deposits	513,011,000	483,956,000
Borrowed funds
Accrued interest payable	38,000	23,000
Total	513,049,000	483,979,000
Borrowed funds
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and cash equivalents
Securities-available for sale	89,614,000	86,880,000
Securities-equities
Loans held for sale	120,000	504,000
Loans, net
Federal bank stock
Accrued interest receivable	353,000	338,000
Total	90,087,000	87,722,000
Accrued interest receivable	353,000	338,000
Total	90,087,000	87,722,000
Financial Liabilities:
Deposits	172,322,000	173,458,000
Borrowed funds	19,414,000	25,499,000
Accrued interest payable	422,000	390,000
Total	192,158,000	199,347,000
Borrowed funds	19,414,000	25,499,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and cash equivalents
Securities-available for sale	3,500,000	7,998,000
Securities-equities		134,000
Loans held for sale
Loans, net	583,741,000	577,616,000
Federal bank stock
Accrued interest receivable	1,861,000	1,820,000
Total	589,102,000	587,568,000
Accrued interest receivable	1,861,000	1,820,000
Total	589,102,000	587,568,000
Financial Liabilities:
Deposits
Borrowed funds
Accrued interest payable
Total
Borrowed funds