Note 5 - Investment Banking and New Issue and Net Trading - Investment Banking and New Issue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Cash revenue	$ 29,500	$ 14,591
Noncash revenue	10,972	18,648
Revenue before gain (loss) on financial instruments	40,472	33,239
New Issue and Advisory [Member]
Revenue	45,711	20,164
Origination [Member]
Cash revenue	0	0
Noncash revenue	0	0
Revenue before gain (loss) on financial instruments	0	0
Cohen & Company Capital Markets (CCM) [Member] | Noncash Consideration [Member]
Gains / (losses) on CCM financial instruments received as non-cash consideration	5,239	(13,075)
Cohen & Company Capital Markets (CCM) [Member] | Underwriting [Member]
Cash revenue	17,395	2,225
Noncash revenue	5,717	1,634
Revenue before gain (loss) on financial instruments	23,112	3,859
Cohen & Company Capital Markets (CCM) [Member] | New Issue and Advisory [Member]
Cash revenue	12,105	12,366
Noncash revenue	5,255	17,014
Revenue before gain (loss) on financial instruments	$ 17,360	$ 29,380