Note 15 - Fair Values of Financial Instruments - Carrying Amount and Fair Value of Financial Instruments Included in the Consolidated Balance Sheet (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Securities, fair value	$ 97,718,000	$ 99,350,000
Equity securities	7,000	1,817,000
Fair Value, Inputs, Level 1 [Member]
Securities, fair value	4,445,000	4,472,000
Equity securities	7,000	1,683,000
Fair Value, Inputs, Level 2 [Member]
Securities, fair value	89,773,000	86,880,000
Equity securities
Fair Value, Inputs, Level 3 [Member]
Securities, fair value	3,500,000	7,998,000
Equity securities		134,000
Reported Value Measurement [Member]
Cash and cash equivalents	17,693,000	14,374,000
Securities, fair value	97,718,000	99,350,000
Equity securities	7,000	1,817,000
Loans held for sale		504,000
Loans, net	708,664,000	577,234,000
Federal bank stock	6,351,000	4,662,000
Accrued interest receivable	2,570,000	2,217,000
Total	833,003,000	700,158,000
Deposits	761,546,000	654,643,000
Borrowed funds	45,350,000	26,000,000
Accrued interest payable	495,000	413,000
Total	807,391,000	681,056,000
Estimate of Fair Value Measurement [Member]
Cash and cash equivalents	17,693,000	14,374,000
Securities, fair value	97,718,000	99,350,000
Equity securities	7,000	1,817,000
Loans held for sale	120,000	504,000
Loans, net	702,747,000	577,616,000
Accrued interest receivable	2,570,000	2,217,000
Total	820,855,000	695,878,000
Deposits	767,009,000	657,414,000
Borrowed funds	44,869,000	25,499,000
Accrued interest payable	495,000	413,000
Total	812,373,000	683,326,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	17,693,000	14,374,000
Securities, fair value	4,445,000	4,472,000
Equity securities	7,000	1,683,000
Loans held for sale
Loans, net
Accrued interest receivable	63,000	59,000
Total	22,208,000	20,588,000
Deposits	539,946,000	483,956,000
Borrowed funds
Accrued interest payable	30,000	23,000
Total	539,976,000	483,979,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents
Securities, fair value	89,773,000	86,880,000
Equity securities
Loans held for sale	120,000	504,000
Loans, net
Accrued interest receivable	351,000	338,000
Total	90,244,000	87,722,000
Deposits	227,063,000	173,458,000
Borrowed funds	44,869,000	25,499,000
Accrued interest payable	465,000	390,000
Total	272,397,000	199,347,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents
Securities, fair value	3,500,000	7,998,000
Equity securities		134,000
Loans held for sale
Loans, net	702,747,000	577,616,000
Accrued interest receivable	2,156,000	1,820,000
Total	708,403,000	587,568,000
Deposits
Borrowed funds
Accrued interest payable
Total