Segment Analysis (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Information concerning assets
Total Assets	$ 625,396	$ 1,229,638
Reportable segments
Information concerning assets
Total Assets	550,737	1,083,846
Investment Banking
Information concerning assets
Total Assets	8,874	15,907
MBS & Rates
Information concerning assets
Total Assets	528,227	1,026,987
Credit Products
Information concerning assets
Total Assets	13,636	40,952
ClearPoint
Information concerning assets
Total Assets	19,100	102,100
Other
Information concerning assets
Total Assets	113,299	197,455
Intersegment eliminations
Information concerning assets
Total Assets	$ (38,640)	$ (51,663)