Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Securities owned, at fair value:	$ 2,557	$ 5,598
Liabilities
Securities sold, not yet purchased, at fair value:	249	2,637
Recurring basis
Assets
Total Assets	2,557	5,631
Liabilities
Securities sold, not yet purchased, at fair value:	249
Total Liabilities	249	2,637
Recurring basis | Tax free money market mutual funds
Assets
Cash and cash equivalents:		33
Recurring basis | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	244	2,571
Liabilities
Securities sold, not yet purchased, at fair value:		2,637
Recurring basis | Mutual funds
Assets
Securities owned, at fair value:	2,313	3,027
Recurring basis | Level 1
Assets
Total Assets	2,557	5,631
Liabilities
Securities sold, not yet purchased, at fair value:	249
Total Liabilities	249	2,637
Recurring basis | Level 1 | Tax free money market mutual funds
Assets
Cash and cash equivalents:		33
Recurring basis | Level 1 | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	244	2,571
Liabilities
Securities sold, not yet purchased, at fair value:		2,637
Recurring basis | Level 1 | Mutual funds
Assets
Securities owned, at fair value:	$ 2,313	$ 3,027