Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Investment Securities and Certificates of Deposit, amortized cost	$ 198,719	$ 813,507
Accounts Receivable, allowances	3,183	2,253
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	$ 154,670	$ 151,455
Treasury Stock, Common, Shares (in shares)	48,206,094	46,651,572
Class A [Member]
Common Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized (in shares)	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued (in shares)	86,863,201	84,767,922
Common Stock, Shares, Outstanding (in shares)	38,657,107	38,116,350
Class B [Member]
Common Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized (in shares)	1,000,000	1,000,000
Common Stock, Shares, Issued (in shares)	47	45
Common Stock, Shares, Outstanding (in shares)	47	45