Note 9 - Share-based Compensation - Stock Options Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Performance based Stock Options [Member]
Expected dividend yield at date of grant	1.44%
Expected stock price volatility	33.83%
Risk-free interest rate	4.13%
Expected life of options (in years) (Year)	4 years
Service based Stock Options [Member]
Expected dividend yield at date of grant	1.94%	2.13%	3.39%
Expected stock price volatility	33.75%	35.12%	35.52%
Risk-free interest rate	4.50%	3.61%	2.33%
Expected life of options (in years) (Year)	5 years	6 years 10 months 6 days	6 years 3 months 14 days