Note 11 - Retirement Plans - Allocation of Plan Assets (Details)	Dec. 31, 2023	Dec. 31, 2022
Plan assets, percent	100.00%	100.00%
Insurance General Account [Member]
Plan assets, percent	13.00%	14.00%
Cash and Cash Equivalents [Member]
Plan assets, percent	4.00%	4.00%
Equity Securities [Member]
Plan assets, percent	50.00%	51.00%
Fixed Income Securities [Member]
Plan assets, percent	30.00%	28.00%
Real Estate [Member]
Plan assets, percent	3.00%	3.00%