Note 7 - Other Long-term Debt - Summary of Other Long-term Debt (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022	Jan. 31, 2022	Jun. 30, 2020
Principal amount	$ 60,155,000	$ 60,155,000
Unamortized debt issuance costs	(1,230,000)	(1,311,000)
5.50% Subordinated Notes Due in 2030 [Member]
Principal amount	15,000,000	15,000,000		$ 15,000,000
Unamortized debt issuance costs	(235,000)	(249,000)
3.50% Subordinated Notes Due in 2032 [Member]
Principal amount	40,000,000	40,000,000	$ 40,000,000
Unamortized debt issuance costs	(995,000)	(1,062,000)
Variable Interest Rate Subordinated Debentures Due in 2035 [Member]
Principal amount	$ 5,155,000	$ 5,155,000