Note 8 - Capital Stock (Details Textual) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		12 Months Ended													125 Months Ended	159 Months Ended
	Apr. 15, 2026	Mar. 31, 2026	Mar. 31, 2025	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	Mar. 31, 2026	Apr. 23, 2026	Oct. 12, 2022	Dec. 09, 2021	Feb. 08, 2018	Jul. 29, 2015
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
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.1
Share Repurchase Program [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)																							400,000
Stock Repurchase Program, Additional Shares Authorized (in shares)																				4,300,000	3,372,399	904,564
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares)																				6,183,601	3,539,861	1,061,315	156,751
Stock Repurchased and Retired During Period, Shares (in shares)		0		1,113,224													6,257,826
Stock Repurchased and Retired During Period, Value				$ 7.3													$ 84.8
Shares Acquired, Average Cost Per Share (in dollars per share)				$ 6.52													$ 13.55
Share Repurchase Program [Member] | Subsequent Event [Member]
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares)																			2,719,137