Segment and Geographic Information (Schedule Of Segment Reporting Information) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net trading		$ 5,988	$ 10,486	$ 20,158	$ 31,973
Asset management		1,779	1,781	6,202	5,662
New issue and advisory		2,012	811	3,992	2,176
Principal transactions and other income		222	1,012	5,515	2,379
Total revenues		10,001	14,090	35,867	42,190
Total operating expenses		9,012	11,439	30,564	36,065
Operating income		989	2,651	5,303	6,125
Interest expense, net		(1,606)	(991)	(4,330)	(2,973)
Income (loss) before income tax expense		(617)	1,660	973	3,152
Income tax expense (benefit)		141	130	148	157
Net income (loss)		(758)	1,530	825	2,995
Less: Net income (loss) attributable to the non-controlling interest		(211)	489	274	925
Net income (loss) attributable to Cohen & Company Inc.		(547)	1,041	551	2,070
Depreciation and amortization (included in total operating expense)		60	66	187	220
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net trading		5,988	10,486	20,158	31,973
Asset management		1,779	1,781	6,202	5,662
New issue and advisory		2,012	811	3,992	2,176
Principal transactions and other income		222	1,012	5,515	2,379
Total revenues		10,001	14,090	35,867	42,190
Total operating expenses		7,190	9,452	24,383	29,425
Operating income		2,811	4,638	11,484	12,765
Income (loss) before income tax expense		2,811	4,638	11,484	12,765
Net income (loss)		2,811	4,638	11,484	12,765
Net income (loss) attributable to Cohen & Company Inc.		2,811	4,638	11,484	12,765
Depreciation and amortization (included in total operating expense)		17	21	54	92
Unallocated [Member]
Segment Reporting Information [Line Items]
Total operating expenses	[1]	1,822	1,987	6,181	6,640
Operating income	[1]	(1,822)	(1,987)	(6,181)	(6,640)
Interest expense, net	[1]	(1,606)	(991)	(4,330)	(2,973)
Income (loss) before income tax expense	[1]	(3,428)	(2,978)	(10,511)	(9,613)
Income tax expense (benefit)	[1]	141	130	148	157
Net income (loss)	[1]	(3,569)	(3,108)	(10,659)	(9,770)
Less: Net income (loss) attributable to the non-controlling interest	[1]	(211)	489	274	925
Net income (loss) attributable to Cohen & Company Inc.	[1]	(3,358)	(3,597)	(10,933)	(10,695)
Depreciation and amortization (included in total operating expense)	[1]	43	45	133	128
Capital Markets [Member]
Segment Reporting Information [Line Items]
Net trading		5,988	10,486	20,158	31,973
New issue and advisory		2,012	811	3,992	2,176
Principal transactions and other income		(2)	30	4	140
Total revenues		7,998	11,327	24,154	34,289
Total operating expenses		6,053	8,556	20,576	26,662
Operating income		1,945	2,771	3,578	7,627
Income (loss) before income tax expense		1,945	2,771	3,578	7,627
Net income (loss)		1,945	2,771	3,578	7,627
Net income (loss) attributable to Cohen & Company Inc.		1,945	2,771	3,578	7,627
Depreciation and amortization (included in total operating expense)		16	20	51	90
Asset Management [Member]
Segment Reporting Information [Line Items]
Asset management		1,779	1,781	6,202	5,662
Principal transactions and other income		230	441	4,995	1,541
Total revenues		2,009	2,222	11,197	7,203
Total operating expenses		1,042	779	3,521	2,394
Operating income		967	1,443	7,676	4,809
Income (loss) before income tax expense		967	1,443	7,676	4,809
Net income (loss)		967	1,443	7,676	4,809
Net income (loss) attributable to Cohen & Company Inc.		967	1,443	7,676	4,809
Depreciation and amortization (included in total operating expense)		1	1	3	2
Principal Investing [Member]
Segment Reporting Information [Line Items]
Principal transactions and other income		(6)	541	516	698
Total revenues		(6)	541	516	698
Total operating expenses		95	117	286	369
Operating income		(101)	424	230	329
Income (loss) before income tax expense		(101)	424	230	329
Net income (loss)		(101)	424	230	329
Net income (loss) attributable to Cohen & Company Inc.		$ (101)	$ 424	$ 230	$ 329

[1] Unallocated includes certain expenses incurred by indirect overhead and support departments (such as the executive, finance, legal, information technology, human resources, risk, compliance, and other similar overhead and support departments). Some of the items not allocated include: (1) operating expenses (such as cash compensation and benefits, equity-based compensation expense, professional fees, travel and entertainment, consulting fees, and rent) related to support departments excluding certain departments that directly support the Capital Markets business segment; (2) interest expense on debt; and (3) income taxes. Management does not consider these items necessary for an understanding of the operating results of these business segments and such amounts are excluded in business segment reporting to the chief operating decision maker.