Note 8 - Capital Stock - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		12 Months Ended														159 Months Ended
		Mar. 31, 2026	Mar. 31, 2025	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	Mar. 31, 2026
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 0.36	$ 0.36		$ 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	$ 69.79
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	$ 984,936
Forecast [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	[1],[2]			$ 0.46
Dividends	[2]			$ 89,100

[1] On April 15, 2026, the Company declared a dividend of $0.10 per share to be paid on May 28, 2026. The effect of this dividend is included in the table above but is not reflected in the Company’s financial statements as of March 31, 2026.

[2] 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