Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Schedule of Investments [Line Items]
Net unrealized gains	$ 32		$ 32		$ 1,193
Unrealized gains during the period, income tax expense	251		251		703
Available-for-sale securities, gross realized gains			394	$ 238
Available-for-sale securities, gross realized losses			535	247
Investment funds sponsored by LSV	3,944		3,944		4,523
Securities owned	21,225		21,225		21,175
Private Equity Funds, Foreign [Member]
Schedule of Investments [Line Items]
Investment funds sponsored by LSV	3,944		3,944		$ 4,523
Realized gains (losses) from investment funds sponsored by LSV	$ (581)	$ (362)	$ (579)	$ 59

Accumulated Other Comprehensive Income (Loss) Available For Sale Securities Adjustment Tax

No definition available.

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- Definition

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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The fair value as of the balance sheet date of firm holdings in debt obligations issued by the US government including short-term Treasury bills, medium-term Treasury notes, and long-term Treasury bonds, as well as debt issued by agencies. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

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All other debt and equity financial instruments, which aren't categorized as available-for-sale, or held-to-maturity and which are not otherwise listed in the existing taxonomy, intended to be held longer than one year from the balance sheet date or the normal operating cycle, if longer.

+ References

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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