Segment Operating Results - Segment Contribution (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net Revenues	$ 689,224	$ 499,419	$ 1,270,039	$ 1,071,562
Operating Expenses	580,981	441,703	1,077,676	904,021
Other Expenses	0	0	0	2,921
Income Before Income from Equity Method Investments and Income Taxes	108,243	57,716	192,363	164,620
Income from Equity Method Investments	1,857	1,542	4,182	3,010
Pre-Tax Income	110,100	59,258	196,545	167,630
Identifiable Segment Assets	3,315,998	3,051,444	3,315,998	3,051,444	$ 3,703,298
Investment Banking and Equities [Member]
Segment Reporting Information [Line Items]
Net Revenues	670,010	482,246	1,231,738	1,037,057
Operating Expenses	566,368	428,344	1,049,206	877,424
Other Expenses	0	0	0	2,921
Income Before Income from Equity Method Investments and Income Taxes	103,642	53,902	182,532	156,712
Income from Equity Method Investments	147	143	835	214
Pre-Tax Income	103,789	54,045	183,367	156,926
Identifiable Segment Assets	3,176,797	2,900,384	3,176,797	2,900,384
Investment Management [Member]
Segment Reporting Information [Line Items]
Net Revenues	19,214	17,173	38,301	34,505
Operating Expenses	14,613	13,359	28,470	26,597
Income Before Income from Equity Method Investments and Income Taxes	4,601	3,814	9,831	7,908
Income from Equity Method Investments	1,710	1,399	3,347	2,796
Pre-Tax Income	6,311	5,213	13,178	10,704
Identifiable Segment Assets	$ 139,201	$ 151,060	$ 139,201	$ 151,060