Note 4 - Allowance for Loan Losses and Impaired Loans (Details Textual)		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loans and Leases Receivable, Allowance, Ending Balance		$ 5,342,000	$ 4,654,000	$ 5,342,000	$ 4,654,000	$ 4,900,000	$ 5,051,000	$ 4,252,000	$ 3,893,000
Provision for Loan and Lease Losses, Total		195,000	$ 414,000	357,000	$ 736,000
Loans and Leases Receivable, Gross, Total		697,379,000		697,379,000		664,095,000
Impaired Financing Receivable, Recorded Investment, Total	[1]	6,016,000		6,016,000		6,169,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	2,844,000		2,844,000		2,580,000
Financing Receivable, Troubled Debt Restructuring		3,500,000		3,500,000		3,900,000
Financing Receivable, Troubled Debt Restructuring, Collectively Evaluated for impairment		2,900,000		2,900,000		3,600,000
Financing Receivable, Troubled Debt Restructuring, Related Allowance		$ 149,000		$ 149,000		192,000
Financing Receivable, Modifications, Number of Contracts		1	3	1	4
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	[2]	0	0	0	0
Financing Receivable, Outstanding Loan Payments Approved for Deferment				$ 66,500,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Ending Balance		$ 0		0		0
Purchase Credit Impaired Loans				0		0
Maximum [Member]
Financing Receivable, Troubled Debt Restructuring		250,000		250,000
Collateral Pledged [Member]
Impaired Financing Receivable, Recorded Investment, Total		3,200,000		3,200,000		3,200,000
Doubtful [Member]
Loans and Leases Receivable, Gross, Total		0		0
Unallocated Financing Receivables [Member]
Provision for Loan and Lease Losses, Total				0
SBA PPP Loans [Member]
Loans and Leases Receivable, Gross, Total		61,454,000		61,454,000		$ 51,118,000
SBA PPP Loans [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Allowance, Ending Balance		$ 0		$ 0

[1] Recorded investment is the loan balance, net of any charge-offs

[2] Loans past due 30 days or more are considered to be in default.