Note 7 - Other Long-term Debt - Summary of Other Long-term Debt (Details) (Parentheticals)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Jan. 31, 2022	Jun. 30, 2020
5.50% Subordinated Notes Due in 2030 [Member]
Debt instrument, fixed interest rate us	5.50%	5.50%		5.50%
Debt instrument, maturity year'	2030	2030
3.50% Subordinated Notes Due in 2032 [Member]
Debt instrument, fixed interest rate us	3.50%		3.50%
Debt instrument, maturity year'	2032
Variable Interest Rate Subordinated Debentures Due in 2035 [Member]
Debt instrument, maturity year'	2035	2035
Variable Interest Rate Subordinated Debentures Due in 2035 [Member] | LIBOR [Member]
Debt instrument, interest rate at 3-month LIBOR	1.42%	1.42%