Segment Operating Results - Segment Contribution (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net Revenues	$ 2,425,949	$ 2,762,048	$ 3,289,499
Operating Expenses	2,063,893	2,062,880	2,178,500
Total Other Expenses	2,921	3,126	8,561
Income Before Income from Equity Method Investments and Income Taxes	359,135	696,042	1,102,438
Income from Equity Method Investments	6,655	7,999	14,161
Pre-Tax Income	365,790	704,041	1,116,599
Identifiable Segment Assets	3,703,298	3,620,923	3,802,657
Investment Banking and Equities [Member]
Segment Reporting Information [Line Items]
Net Revenues	2,355,943	2,696,125	3,223,889
Operating Expenses	2,010,757	2,009,913	2,125,871
Total Other Expenses	2,921	3,126	7
Income Before Income from Equity Method Investments and Income Taxes	342,265	683,086	1,098,011
Income from Equity Method Investments	620	1,217	1,337
Pre-Tax Income	342,885	684,303	1,099,348
Identifiable Segment Assets	3,541,886	3,446,075	3,605,332
Investment Management [Member]
Segment Reporting Information [Line Items]
Net Revenues	70,006	65,923	65,610
Operating Expenses	53,136	52,967	52,629
Total Other Expenses	0	0	8,554
Income Before Income from Equity Method Investments and Income Taxes	16,870	12,956	4,427
Income from Equity Method Investments	6,035	6,782	12,824
Pre-Tax Income	22,905	19,738	17,251
Identifiable Segment Assets	$ 161,412	$ 174,848	$ 197,325