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Summary Of Significant Accounting Policies [Line Items]

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Amount of income tax expense (benefit) for remeasurement of deferred tax from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount of increase (decrease) in operating liabilities classified as other.

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Amount of increase (decrease) in receivables classified as other.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Amount of assets classified as other.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Other assets	$ 1,672	$ 3,621	$ 1,672
Tax benefit from Tax Cuts and Jobs Act	1,359
Estimated debt in fair value	$ 53,657	50,159	53,657
Increase in other receivables		8,559	$ (1,712)	$ 1,146
Accounting Standards Update 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right of use asset		8,416
Lease commitment liability		8,860
Reduction in retained earnings from cumulative effect of adoption		20
Increase in other receivables		18
Reduction in other liabilities		$ 406
COHN, LLC [Member]
Summary Of Significant Accounting Policies [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	68.60%	67.60%	68.60%
CDOs [Member]
Summary Of Significant Accounting Policies [Line Items]
Total revenue		$ 7,919
Other Investment Funds [Member]
Summary Of Significant Accounting Policies [Line Items]
Total revenue		$ 4,617
Maximum [Member] \| CDOs [Member]
Summary Of Significant Accounting Policies [Line Items]
Incentive management fee, payout period		7 years
Minimum [Member] \| CDOs [Member]
Summary Of Significant Accounting Policies [Line Items]
Incentive management fee, payout period		5 years
Restatement Adjustment [Member] \| Accounting Standards Update 2015-03 [Member]
Summary Of Significant Accounting Policies [Line Items]
Other assets					$ (410)
Debt					$ (410)
Furniture and Equipment [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Furniture and Equipment [Member] \| Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Leasehold Improvements [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		10 years
Leasehold Improvements [Member] \| Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		5 years