Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investment Securities and Certificates of Deposit, amortized cost	$ 744,178	$ 802,652
Accounts Receivable, allowances	5,603	4,683	$ 2,704
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	$ 212,929	$ 187,077
Treasury Stock, Common, Shares	44,340,396	41,339,113
Class A [Member]
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	82,114,009	79,686,375
Common Stock, Shares, Outstanding	37,773,613	38,347,262
Class B [Member]
Common Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000	1,000,000
Common Stock, Shares, Issued	46	50
Common Stock, Shares, Outstanding	46	50