Note 9 - Incentive Plans - Number of Shares Available for Grant Pursuant to Long-term Incentive Plan (Details) - shares	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Awards issued under plan (in shares)	(13,449,061)	(11,517,228)	(9,983,727)
The 2020 Long-term Incentive Plan [Member]
Approved and authorized awards (in shares)	16,414,015	14,340,324
Awards issued under plan (in shares)	(15,759,791)	(13,769,191)
Awards available for future grant (in shares)	654,224	571,133