Note 8 - Capital Stock - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended														156 Months Ended
		Dec. 31, 2026	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2025
Common Stock, Dividends, Per Share, Declared (in dollars per share)			$ 1.44	$ 1.44	$ 1.8	$ 2.475	$ 3.9	$ 3.95	$ 4.8	$ 5.35	$ 8.4	$ 8.4	$ 9.6	$ 10.8	$ 6.975	$ 69.57
Dividends			$ 190,930	$ 96,309	$ 81,127	$ 87,906	$ 97,601	$ 53,570	$ 54,421	$ 55,814	$ 70,717	$ 41,388	$ 38,748	$ 22,643	$ 4,662	$ 940,793
Forecast [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	[1],[2]	$ 0.24
Dividends	[1]	$ 44,957

[1] On January 7, 2026, the Company declared a dividend of $0.12 per share to be paid on February 26, 2026. On February 11, 2026, the Company declared a dividend of $0.12 per share to be paid on March 30, 2026. The effect of these dividends are included in the table above, but are not reflected in the Company’s financial statements as of December 31, 2025

[2] On October 15, 2025, the Company declared a dividend of $0.12 per share to be paid on November 26, 2025. The effect of this dividend is included in the table above but is not reflected in the Company’s financial statements as of September 30, 2025.