Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Dec. 31, 2015 |
|
| Schedule of Investments [Line Items] | |||||
| Net unrealized gains (losses) | $ 154 | $ 154 | $ (302) | ||
| Unrealized gains (losses) during the period, income tax expense (benefit) | 246 | 246 | (43) | ||
| Available-for-sale securities, gross realized gains | 270 | $ 394 | |||
| Available-for-sale securities, gross realized losses | 679 | 535 | |||
| Investment funds sponsored by LSV | 4,888 | 4,888 | 4,039 | ||
| Securities owned | 21,320 | 21,320 | 21,235 | ||
| Private Equity Funds, Foreign [Member] | |||||
| Schedule of Investments [Line Items] | |||||
| Investment funds sponsored by LSV | 4,888 | 4,888 | $ 4,039 | ||
| Realized gains (losses) from investment funds sponsored by LSV | $ 468 | $ (581) | $ 849 | $ (579) | |