Note 10 - Other Long-term Debt - Summary of Other Long-term Debt (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2017	Jun. 30, 2015
Principal amount	$ 25,155,000	$ 25,155,000
Unamortized debt issuance costs	(214,000)	(279,000)
5.75% Senior Unsecured Notes Due February 15, 2022 [Member]
Principal amount	10,000,000	10,000,000	$ 10,000,000
Unamortized debt issuance costs	(92,000)	(136,000)
6.75% Subordinated Notes Due in 2025 [Member]
Principal amount	10,000,000	10,000,000		$ 10,000,000
Unamortized debt issuance costs	(122,000)	(143,000)
Variable Interest Rate Subordinated Debentures Due in 2035 [Member]
Principal amount	5,155,000	5,155,000
Unamortized debt issuance costs