Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts receivable, allowance for credit losses	$ 4,511	$ 4,088
Treasury stock, shares	3,683,415	2,757,558
Class A Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	59,144,937	52,773,617
Common stock, shares outstanding	55,461,522	50,016,059
Treasury stock, shares	3,683,415	2,757,558
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	8,490,938	10,397,915
Common stock, shares outstanding	8,490,938	10,397,915