Consolidated Statements of Financial Condition (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Cash and cash equivalents, restricted from use	$ 5,100,000	$ 7,100,000
Advisory fees receivable, allowance for doubtful accounts	0	0
Property and equipment, accumulated depreciation	$ 56,951,000	$ 54,760,000
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, shares issued (shares)	37,872,756	36,513,507
Common stock, shares outstanding (shares)	27,767,702	27,488,828
Contingent convertible preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Contingent convertible preferred stock, shares authorized (shares)	10,000,000	10,000,000
Contingent convertible preferred stock, shares issued (shares)	1,099,877	1,099,877
Contingent convertible preferred stock, shares outstanding (shares)	439,951	1,099,877
Exchangeable shares of subsidiary, shares issued (shares)	257,156	257,156
Exchangeable shares of subsidiary, shares outstanding (shares)	32,804	32,804
Treasury stock, par value (usd per share)	$ 0.01	$ 0.01
Treasury stock, shares (shares)	10,105,054	9,024,679