Note 26 - Earnings (Loss) Per Common Share- Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Net Income (Loss) Attributable to Parent		$ 14,751	$ 1,655	$ 901	$ (3,102)	$ 774	$ (1,216)	$ (410)	$ (1,202)	$ 14,205		$ (2,054)		$ (2,463)
Add/ (deduct): Income / (loss) attributable to non-controlling interest attributable to Operating LLC membership (1)	[1]									14,200		(1,231)		(1,524)
Add back: interest expense on 2017 Convertible Note, net of tax										1,162
Add / (deduct): Adjustment (2)	[2]									9,452		246		390
Net income / (loss) on a fully converted basis										$ 39,019		$ (3,039)		$ (3,597)
Weighted average shares outstanding-basic (in shares)		1,070,377	1,146,941	1,160,144	1,146,879	1,125,311	1,143,909	1,143,909	1,133,166	1,131,085		1,136,574		1,152,073
Unrestricted Operating LLC units of membership interests exchangeable into Cohen & Company Inc. shares (1) (in shares)	[1]									2,800,597		544,599		532,409
Restricted Units or shares (in shares)										124,922
Contingent shares on the 2017 Convertible Note (in shares)										1,034,483
Weighted average common shares outstanding - Diluted (in shares)		5,207,263	5,115,583	5,020,453	3,940,677	2,757,194	1,676,318	1,676,318	1,665,575	5,091,087		1,681,173		1,684,482
Basic income / (loss) per common share (in dollars per share)		$ 13.78	$ 1.44	$ 0.78	$ (2.70)	$ 0.69	$ (1.06)	$ (0.36)	$ (1.06)	$ 12.56		$ (1.81)		$ (2.14)
Diluted Income / (loss) per common share (in dollars per share)		$ 7.64	$ 1.19	$ 0.69	$ (2.70)	$ 0.56	$ (1.06)	$ (0.36)	$ (1.06)	$ 7.66	[3]	$ (1.81)	[3]	$ (2.14)	[3]

[1] The Operating LLC units of membership interests not held by Cohen & Company Inc. (that is, those held by the non-controlling interest) may be redeemed and exchanged into shares of the Company on a ten-for-one basis. The Operating LLC units of membership interests not held by Cohen & Company Inc. are redeemable, at the member's option at any time, for (i) cash in an amount equal to the average of the per share closing prices of the Common Stock for the ten consecutive trading days immediately preceding the date the Company receives the member's redemption notice, or (ii) at the Company's option, one tenth of a share of the Common Stock, subject, in each case, to appropriate adjustment upon the occurrence of an issuance of additional shares of the Common Stock as a dividend or other distribution on the outstanding Common Stock, or a further subdivision or combination of the outstanding shares of the Common Stock. These units are not included in the computation of basic earnings per share. These units enter into the computation of diluted net income (loss) per common share when the effect is not anti-dilutive using the if-converted method.

[2] An adjustment is included because the Company would have incurred a higher income tax expense or realized a higher income tax benefit if the Operating LLC units of membership interests had been converted at the beginning of the period.

[3] Potentially diluted securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: Year Ended December 31, 2020 2019 2018 2017 Convertible Note 1,034,483 1,034,483 - 2013 Convertible Notes 414,882 352,292 274,917 Restricted Common Stock 15,101 26,380 - Restricted Operating LLC units 3,752 - - 1,468,218 1,413,155 274,917