Note 6 - Leases - Lease Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Right-of-use assets	$ 4,040		$ 4,040		$ 4,878
Weighted average remaining lease term (years) (Year)	7 years 1 month 13 days		7 years 1 month 13 days		7 years 3 months 29 days
Weighted average discount rate	3.15%		3.15%		3.03%
Operating lease cost	$ 267	$ 243	$ 804	$ 742
Short-term lease cost	0	1	0	2
Total lease cost	267	244	804	744
Cash paid for amounts included in the measurement of lease liabilities	265	$ 237	781	$ 722
Other Liabilities [Member]
Lease liabilities	$ 4,119		$ 4,119		$ 4,940