Debt (Debt Outstanding) (Details)		3 Months Ended
		Mar. 31, 2018 USD ($) $ / shares	Mar. 31, 2017	Dec. 31, 2017 USD ($) $ / shares
Debt Instrument [Line Items]
Long term debt less debt discount		$ 44,403,000		$ 44,177,000
Redeemable noncontrolling interest, membership units not held, share ratio		10	10
Common Stock, Par or Stated Value Per Share | $ / shares		$ 0.01		$ 0.01
Contingent Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Less unamortized debt issuance costs		$ (1,245,000)		$ (1,343,000)
Long term debt less debt discount		22,003,000		21,905,000
Junior subordinated debt [Member]
Debt Instrument [Line Items]
Less unamortized debt issuance costs	[1]	(25,725,000)		(25,853,000)
Long term debt less debt discount	[1]	22,400,000		22,272,000
Junior subordinated notes		49,614,000
Ownership value of common stock of trusts		$ 1,489,000
8.00% Contingent Convertible Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Conversion Price | $ / shares		$ 1.45
8.00% Contingent Convertible Senior Notes Due 2022 [Member] | Contingent Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	[2]	$ 15,000,000		15,000,000
Interest Rate	[2],[3]	8.00%
Maturity	[2]	Mar. 31, 2022
Debt Instrument, Convertible, Conversion Price | $ / shares		$ 1.00
Debt instrument, noncontrolling interests, convertible price | $ / shares		$ 14.50
Debt Instrument, Convertible, Conversion Ratio		10
8.00% Contingent Convertible Senior Notes Due 2018 [Member] | Contingent Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	[4]	$ 8,248,000		8,248,000
Interest Rate	[3],[4]	8.00%
Maturity	[4]	Sep. 30, 2018
Debt Instrument, Convertible, Conversion Price | $ / shares		$ 30.00
Alesco Capital Trust I [Member] | Junior subordinated debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	[1]	$ 28,125,000		28,125,000
Interest Rate	[1],[3]	5.77%
Maturity	[1]	Jul. 31, 2037
Sunset Financial Statutory Trust I [Member] | Junior subordinated debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	[1]	$ 20,000,000		$ 20,000,000
Interest Rate	[1],[3]	6.46%
Maturity	[1]	Mar. 31, 2035
Fair value of common securities		$ 0

[1] The junior subordinated notes listed represent debt the Company owes to the two trusts noted above. The total par amount owed by the Company to the trusts is $49,614. However, the Company owns the common stock of the trusts in a total par amount of $1,489. The Company pays interest (and at maturity, principal) to the trusts on the entire $49,614 junior notes outstanding. However, the Company receives back from the trusts the pro rata share of interest and principal on the common stock held by the Company. These trusts are VIEs and the Company does not consolidate them even though the Company holds common stock. The Company carries the common stock on its balance sheet at a value of $0.

[2] The holder of the 2017 Convertible Note may convert all or any part of the outstanding principal amount of the 2017 Convertible Note at any time prior to maturity into units of the Operating LLC at a conversion price of $1.45 per unit, subject to customary anti-dilution adjustments. Units of the Operating LLC not held by Cohen & Company Inc. may, with certain restrictions, be redeemed and exchanged into shares of the Company’s Common Stock on a ten-for-one basis. Therefore, the 2017 Convertible Note can be converted into Operating LLC units and then redeemed and exchanged into Common Stock at an effective conversion price of $14.50. See discussion below and note 17 to our Annual Report on Form 10-K for the year ended December 31, 2017.

[3] Represents the interest rate in effect as of the last day of the reporting period.

[4] The holders of the 2013 Convertible Notes may convert all or any part of the outstanding principal amount of the 2013 Convertible Notes at any time prior to maturity into shares of the Company's Common Stock at a conversion price of $30.00 per share, subject to customary anti-dilution adjustments.