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, 2019	Dec. 31, 2018
Debt securities, fair value	$ 120,107,000	$ 97,718,000
Securities - equities	19,000	7,000
Federal bank stock	5,790,000	6,351,000
Fair Value, Inputs, Level 1 [Member]
Debt securities, fair value		4,445,000
Securities - equities	19,000	7,000
Fair Value, Inputs, Level 2 [Member]
Debt securities, fair value	115,857,000	89,773,000
Securities - equities
Fair Value, Inputs, Level 3 [Member]
Debt securities, fair value	4,250,000	3,500,000
Securities - equities
Reported Value Measurement [Member]
Cash and cash equivalents	14,986,000	10,955,000
Interest earning time deposits	9,698,000	6,738,000
Debt securities, fair value	120,107,000	97,718,000
Securities - equities	19,000	7,000
Loans, net	695,348,000	708,664,000
Federal bank stock	5,790,000	6,351,000
Accrued interest receivable	2,600,000	2,570,000
Total	848,548,000	833,003,000
Deposits	787,124,000	761,546,000
Borrowed funds	28,550,000	45,350,000
Accrued interest payable	616,000	495,000
Total	816,290,000	807,391,000
Estimate of Fair Value Measurement [Member]
Cash and cash equivalents	14,986,000	10,955,000
Interest earning time deposits	9,698,000	6,738,000
Debt securities, fair value	120,107,000	97,718,000
Securities - equities	19,000	7,000
Loans, net	697,990,000	702,747,000
Federal bank stock
Accrued interest receivable	2,600,000	2,570,000
Total	845,400,000	820,735,000
Deposits	793,999,000	767,009,000
Borrowed funds	29,133,000	44,869,000
Accrued interest payable	616,000	495,000
Total	823,748,000	812,373,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	14,986,000	10,955,000
Interest earning time deposits
Debt securities, fair value		4,445,000
Securities - equities	19,000	7,000
Loans, net
Federal bank stock
Accrued interest receivable	78,000	63,000
Total	15,083,000	15,470,000
Deposits	569,357,000	539,946,000
Borrowed funds
Accrued interest payable	51,000	30,000
Total	569,408,000	539,976,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents
Interest earning time deposits	9,698,000	6,738,000
Debt securities, fair value	115,857,000	89,773,000
Securities - equities
Loans, net
Accrued interest receivable	419,000	351,000
Total	125,974,000	96,862,000
Deposits	224,642,000	227,063,000
Borrowed funds	29,133,000	44,869,000
Accrued interest payable	565,000	465,000
Total	254,340,000	272,397,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents
Interest earning time deposits
Debt securities, fair value	4,250,000	3,500,000
Securities - equities
Loans, net	697,990,000	702,747,000
Federal bank stock
Accrued interest receivable	2,103,000	2,156,000
Total	704,343,000	708,403,000
Deposits
Borrowed funds
Accrued interest payable
Total