Condensed Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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	385,857,000	373,545,000
Common stock, shares outstanding	334,364,000	323,018,000
Treasury stock, at cost	51,492,000	50,527,000
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	45,884,000	45,884,000
Common stock, shares outstanding	45,884,000	45,884,000