Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets
Securities owned, at fair value:	$ 7,436	$ 10,086
Liabilities
Securities sold, not yet purchased, at fair value:	2,953	5,249
Recurring basis | Total
Assets
Total Assets	10,164	118,075
Liabilities
Total Liabilities	2,953	5,249
Recurring basis | Total | Tax free money market mutual funds
Assets
Cash and cash equivalents:	33	4,555
Recurring basis | Total | U.S. government money market mutual funds
Assets
Cash and cash equivalents:		97,203
Recurring basis | Total | Money market mutual funds
Assets
Cash and cash equivalents:	2,695	6,231
Recurring basis | Total | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	2,894	5,438
Liabilities
Securities sold, not yet purchased, at fair value:	2,953	5,249
Recurring basis | Total | Mutual funds
Assets
Securities owned, at fair value:	4,542	4,648
Recurring basis | Level 1
Assets
Total Assets	10,164	118,075
Liabilities
Total Liabilities	2,953	5,249
Recurring basis | Level 1 | Tax free money market mutual funds
Assets
Cash and cash equivalents:	33	4,555
Recurring basis | Level 1 | U.S. government money market mutual funds
Assets
Cash and cash equivalents:		97,203
Recurring basis | Level 1 | Money market mutual funds
Assets
Cash and cash equivalents:	2,695	6,231
Recurring basis | Level 1 | Corporate stocks-trading securities
Assets
Securities owned, at fair value:	2,894	5,438
Liabilities
Securities sold, not yet purchased, at fair value:	2,953	5,249
Recurring basis | Level 1 | Mutual funds
Assets
Securities owned, at fair value:	$ 4,542	$ 4,648