Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Investments [Line Items]
Net unrealized losses	$ (207)		$ (207)		$ (836)
Unrealized losses during the period, income tax benefit	(68)		(68)		(299)
Available-for-sale securities, gross realized gains			428	$ 270
Available-for-sale securities, gross realized losses			706	679
Fair value of investment funds sponsored by LSV	5,738		5,738		4,858
Securities owned	21,469		21,469		21,339
Investment Funds Sponsored by LSV [Member]
Schedule of Investments [Line Items]
Fair value of investment funds sponsored by LSV	5,738		5,738		$ 4,858
Gains from investment funds sponsored by LSV	$ 388	$ 468	$ 880	$ 849

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

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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
-SubTopic 10
-Section 45
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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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.

+ References

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Amount of debt and equity financial instruments classified as other and noncurrent.

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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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