Note 8 - Financial Instruments - Financial Instruments Sold, Not Yet Purchased (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investment securities sold, not yet purchased	$ 133,957	$ 62,512
Other investments sold, not yet purchased	78	2,488
Equity Securities [Member]
Investment securities sold, not yet purchased	51	0
Other investments sold, not yet purchased	78	2,488
Corporate Bonds and Redeemable Preferred Stock [Member]
Investment securities sold, not yet purchased	61,310	32,574
Derivative [Member]
Investment securities sold, not yet purchased	1,177	424
US Treasury Securities [Member]
Investment securities sold, not yet purchased	71,386	29,513
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment securities sold, not yet purchased	1	1
US Government Agencies Debt Securities [Member]
Investment securities sold, not yet purchased	$ 32	$ 0