Note 10 - Collateralized Securities Transactions (Details Textual) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Securities Purchased under Agreements to Resell	$ 359,602		$ 357,408
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	359,726		360,586
Securities Sold under Agreements to Repurchase	402,389		400,391
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	406,111		$ 407,075
Revenues	$ 57,902	$ 28,740
Securities Sold under Agreements to Repurchase, Average Rate Paid	4.41%		4.47%
Securities Purchased under Agreements to Resell, Average Rate	4.83%		4.98%
Gestational Repo Business [Member]
Revenues	$ 5,885	$ 4,179