Note 11 - Retirement Plans - Allocation of Plan Assets (Details)	Dec. 31, 2021	Dec. 31, 2020
Plan assets, percent	100.00%	100.00%
Insurance General Account [Member]
Plan assets, percent	13.00%	15.00%
Cash and Cash Equivalents [Member]
Plan assets, percent	2.00%	3.00%
Equity Securities [Member]
Plan assets, percent	50.00%	48.00%
Fixed Income Securities [Member]
Plan assets, percent	33.00%	32.00%
Real Estate [Member]
Plan assets, percent	2.00%	2.00%