Fair Value of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Schedule of Trading Securities and Other Trading Assets [Line Items] | ||
| Securities owned deposited with the Company's subsidiaries clearing broker | $ 3,265 | $ 3,161 |
| Securities owned, at fair value | 3,881 | 3,543 |
| Common Stock and Warrants | Warrants to purchase common stock | Level 2 | ||
| Schedule of Trading Securities and Other Trading Assets [Line Items] | ||
| Securities owned, at fair value | $ 475 | $ 252 |
| X | ||||||||||
- Definition Securities owned and held at clearing broker. No definition available.
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Fair value of financial instruments held by a broker-dealer for their own account (proprietary securities) for trading or investment purposes determined by management based upon quoted prices of a financial instrument with similar characteristics or on a valuation technique or model. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|