Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Condensed Consolidated Statements of Financial Condition
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	52,037,011	51,899,229
Common stock held in treasury, shares	14,078,344	12,679,948