Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale, Amortized Cost	$ 286,567	$ 706,826
Accounts Receivable, Allowances	2,054	2,704
Furniture, Equipment and Leasehold Improvements, Accumulated Depreciation and Amortization	172,091	165,857
Intangible Assets, Accumulated Amortization	$ 3,384	$ 3,294
Treasury Stock at Cost, shares	38,891,974	36,900,858
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	79,460,450	74,804,288
Common Stock, Shares, Outstanding	40,568,476	37,903,430
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	50	53
Common Stock, Shares, Outstanding	50	53