Note 3 - Cash, Cash Equivalents and Restricted Cash (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2022
Average Excess Balances Maintained With Federal Reserve Bank	$ 1,240,000	$ 1,610,000
Margin Deposit Assets	88,900	24,300
Restricted Cash, Total	25,400	690
Bank [Member]
Restricted Cash, Total	$ 8,200	$ 5,900	$ 0