Note 10 - Other Long-term Debt - Summary of Other Long-term Debt (Details) (Parentheticals)	1 Months Ended		12 Months Ended
	Feb. 28, 2017	Jun. 30, 2015	Dec. 31, 2019	Dec. 31, 2018
5.75% Senior Unsecured Notes Due February 15, 2022 [Member]
Debt instrument, fixed interest rate	5.75%		5.75%	5.75%
Debt instrument, maturity year	2022		2022	2022
6.75% Subordinated Notes Due in 2025 [Member]
Debt instrument, fixed interest rate		6.75%	6.75%	6.75%
Debt instrument, maturity year		2025	2025	2025
Variable Interest Rate Subordinated Debentures Due in 2035 [Member]
Debt instrument, maturity year			2035	2035
Variable Interest Rate Subordinated Debentures Due in 2035 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt instrument, interest rate at 3-month LIBOR			1.42%	1.42%