Note 8 - Capital Stock (Details Textual) - USD ($)		3 Months Ended				9 Months Ended	11 Months Ended		12 Months Ended												122 Months Ended	153 Months Ended
	Oct. 15, 2025	Sep. 30, 2025	Jun. 30, 2025	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Nov. 26, 2025	[1],[2]	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	Sep. 30, 2025	Sep. 30, 2025	Oct. 24, 2025	Oct. 12, 2022	Dec. 09, 2021	Feb. 08, 2018	Jul. 29, 2015
Common Stock, Shares Authorized (in shares)		200,000,000				200,000,000			200,000,000												200,000,000	200,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.01				$ 0.01			$ 0.01												$ 0.01	$ 0.01
Preferred Stock, Shares Authorized (in shares)		20,000,000				20,000,000			20,000,000												20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.01				$ 0.01			$ 0.01												$ 0.01	$ 0.01
Stock Repurchased and Retired During Period, Value			$ 7,260,000	$ 512,000	$ 2,778,000
Common Stock, Dividends, Per Share, Declared (in dollars per share)							$ 1.2		$ 1.44	$ 1.8	$ 2.475	$ 3.9	$ 3.95	$ 4.8	$ 5.35	$ 8.4	$ 8.4	$ 9.6	$ 10.8	$ 6.975		$ 69.09
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)		2,719,137				2,719,137															2,719,137	2,719,137		6,183,601	3,539,861	1,061,315	156,751
Stock Repurchased and Retired During Period, Shares (in shares)		0				1,113,224			396,241												6,257,826
Stock Repurchased and Retired During Period, Value						$ 7,300,000			$ 3,300,000												$ 84,800,000
Shares Acquired, Average Cost Per Share (in dollars per share)						$ 6.52			$ 8.3												$ 13.55
Subsequent Event [Member]
Total Number Of Shares Authorized (in shares)																							420,000,000
Common Stock, Shares Authorized (in shares)																							400,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)																							$ 0.01
Preferred Stock, Shares Authorized (in shares)																							20,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)																							$ 0.01
Aggregate Par Value of Authorized Shares																							$ 4,200,000
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.12

[1] On July 9, 2025, the Company declared a dividend of $0.12 per share to be paid on August 28, 2025. The effect of this dividend is included in the table above but is not reflected in the Company’s financial statements as of June 30, 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.