Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Investments [Line Items]
Net unrealized gains		$ 649		$ 1,193
Unrealized gains during the period, income tax expense		389		703
Available-for-sale securities, gross realized gains		357	$ 230
Available-for-sale securities, gross realized losses		320	123
Investment funds sponsored by LSV		4,525		4,523
Securities owned		21,204		21,175
Private Equity Funds, Foreign [Member]
Schedule of Investments [Line Items]
Investment funds sponsored by LSV		$ 4,525		$ 4,523
Realized gains from investment funds sponsored by LSV	$ 356		$ 421