Condensed Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Class A Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	299,722,000	292,549,000
Common stock, shares outstanding	251,057,000	244,870,000
Treasury stock, at cost	48,665,000	47,679,000
Class B Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	34,848,000	34,848,000
Common stock, shares outstanding	34,848,107	34,848,000