Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Securities owned, at fair value:	$ 5,598	$ 12,073
Liabilities
Securities sold, not yet purchased, at fair value:	2,637	8,253
Recurring basis | Level 1
Assets
Total Assets	5,631	19,071
Liabilities
Total Liabilities	2,637	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:		6,965
Recurring basis | Level 1 | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	2,571	8,160
Liabilities
Securities sold, not yet purchased, at fair value:	2,637	8,253
Recurring basis | Level 1 | Mutual funds
Assets
Securities owned, at fair value:	3,027	3,913
Recurring basis | Total
Assets
Total Assets	5,631	19,071
Liabilities
Total Liabilities	2,637	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:		6,965
Recurring basis | Total | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	2,571	8,160
Liabilities
Securities sold, not yet purchased, at fair value:	2,637	8,253
Recurring basis | Total | Mutual funds
Assets
Securities owned, at fair value:	$ 3,027	$ 3,913