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Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Dec. 31, 2015
Schedule of Investments [Line Items] |  |  |
Net unrealized gains (losses) | $ 215 |  | $ (302)
Unrealized gains (losses) during the period, income tax expense (benefit) | 251 |  | (43)
Available-for-sale securities, gross realized gains | 13 | $ 288 |
Available-for-sale securities, gross realized losses | 303 | 142 |
Investment funds sponsored by LSV | 4,183 |  | 4,039
Securities owned | 21,264 |  | 21,235
Private Equity Funds, Foreign [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Investment funds sponsored by LSV | 4,183 |  | $ 4,039
Realized gains (losses) from investment funds sponsored by LSV | $ 144 | $ (69) |

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