Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized	5,000	5,000
Convertible preferred stock, shares issued
Convertible preferred stock, shares outstanding
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000	50,000
Common stock, shares issued	25,252	23,191
Common stock, shares outstanding	25,252	23,191