Note 4 - Allowance for Loan Losses and Reserve for Unfunded Lending Commitments (Details Textual) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable, Allowance, Ending Balance	$ 20,630,000		$ 21,088,000	$ 20,630,000	$ 21,088,000	$ 21,403,000	$ 13,152,000
Provision for Loan and Lease Losses, Total	482,000	$ (1,400,000)	$ 2,619,000	(870,000)	$ 8,331,000	8,916,000
SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Allowance, Ending Balance	$ 0			$ 0		$ 0