Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets
Securities owned, at fair value:	$ 10,612	$ 12,073
Liabilities
Securities sold, not yet purchased, at fair value:	6,996	8,253
Recurring basis | Total
Assets
Total Assets	16,415	19,071
Liabilities
Total Liabilities	6,996	8,253
Recurring basis | Total | Tax free money market mutual funds
Assets
Cash and cash equivalents:	33	33
Recurring basis | Total | Money market mutual funds
Assets
Cash and cash equivalents:	5,770	6,965
Recurring basis | Total | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	7,087	8,160
Liabilities
Securities sold, not yet purchased, at fair value:	6,996	8,253
Recurring basis | Total | Mutual funds
Assets
Securities owned, at fair value:	3,525	3,913
Recurring basis | Level 1
Assets
Total Assets	16,415	19,071
Liabilities
Total Liabilities	6,996	8,253
Recurring basis | Level 1 | Tax free money market mutual funds
Assets
Cash and cash equivalents:	33	33
Recurring basis | Level 1 | Money market mutual funds
Assets
Cash and cash equivalents:	5,770	6,965
Recurring basis | Level 1 | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	7,087	8,160
Liabilities
Securities sold, not yet purchased, at fair value:	6,996	8,253
Recurring basis | Level 1 | Mutual funds
Assets
Securities owned, at fair value:	$ 3,525	$ 3,913