Annual report pursuant to Section 13 and 15(d)

Securities Owned and Securities Sold, But Not Yet Purchased (Fair Value Amount) (Details)

v3.3.1.900
Securities Owned and Securities Sold, But Not Yet Purchased (Fair Value Amount) (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value $ 4,079 $ 5,910
Securities sold, but not yet purchased, at fair value (238) (230)
Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 1,286 2,446
Securities sold, but not yet purchased, at fair value (8) (34)
Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 2,793 3,464
Securities sold, but not yet purchased, at fair value (230) (196)
Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
Certificates of Deposit    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 359 465
Securities sold, but not yet purchased, at fair value 0 0
Certificates of Deposit | Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 359 465
Securities sold, but not yet purchased, at fair value 0  
Certificates of Deposit | Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0  
Certificates of Deposit | Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0  
Debt Securities    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 1,125 1,526
Securities sold, but not yet purchased, at fair value (30) (45)
Debt Securities | Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
Debt Securities | Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 1,125 1,526
Securities sold, but not yet purchased, at fair value (30) (45)
Debt Securities | Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
U.S. Treasury Notes    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 101 102
Securities sold, but not yet purchased, at fair value (200) (151)
U.S. Treasury Notes | Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
U.S. Treasury Notes | Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 101 102
Securities sold, but not yet purchased, at fair value (200) (151)
U.S. Treasury Notes | Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
Common Stock and Warrants    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 1,885 2,856
Securities sold, but not yet purchased, at fair value (8) (34)
Common Stock and Warrants | Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 927 1,981
Securities sold, but not yet purchased, at fair value (8) (34)
Common Stock and Warrants | Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 958 875
Securities sold, but not yet purchased, at fair value 0 0
Common Stock and Warrants | Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Securities sold, but not yet purchased, at fair value 0 0
Other Investments    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 609 961
Securities sold, but not yet purchased, at fair value 0 0
Other Investments | Level 1    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 0 0
Other Investments | Level 2    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value 609 961
Other Investments | Level 3    
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]    
Securities owned at fair value $ 0 $ 0