Segment Operating Results - Segment Contribution (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Net Revenues	$ 694,829	$ 580,815
Employee Compensation and Benefits	459,825	387,705
Non-Compensation	123,820	108,990
Income Before Income from Equity Method Investments and Income Taxes	111,184	84,120
Income (Loss) from Equity Method Investments	879	2,325
Pre-Tax Income	112,063	86,445
Identifiable Segment Assets	3,271,115	3,005,988	$ 4,173,971
Investment Banking & Equities
Segment Reporting Information [Line Items]
Net Revenues	674,532	561,728
Employee Compensation and Benefits	448,029	377,287
Non-Compensation	119,774	105,551
Income Before Income from Equity Method Investments and Income Taxes	106,729	78,890
Income (Loss) from Equity Method Investments	(38)	688
Pre-Tax Income	106,691	79,578
Identifiable Segment Assets	3,178,276	2,879,890
Investment Management
Segment Reporting Information [Line Items]
Net Revenues	20,297	19,087
Employee Compensation and Benefits	11,796	10,418
Non-Compensation	4,046	3,439
Income Before Income from Equity Method Investments and Income Taxes	4,455	5,230
Income (Loss) from Equity Method Investments	917	1,637
Pre-Tax Income	5,372	6,867
Identifiable Segment Assets	$ 92,839	$ 126,098