Segment Operating Results - Segment Contribution (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net Revenues	$ 580,815	$ 572,143
Operating Expenses	496,695	462,318
Other Expenses	0	2,921
Income Before Income from Equity Method Investments and Income Taxes	84,120	106,904
Income from Equity Method Investments	2,325	1,468
Pre-Tax Income	86,445	108,372
Identifiable Segment Assets	3,005,988	2,750,472	$ 3,703,298
Investment Banking and Equities [Member]
Segment Reporting Information [Line Items]
Net Revenues	561,728	554,811
Operating Expenses	482,838	449,080
Other Expenses	0	2,921
Income Before Income from Equity Method Investments and Income Taxes	78,890	102,810
Income from Equity Method Investments	688	71
Pre-Tax Income	79,578	102,881
Identifiable Segment Assets	2,879,890	2,608,350
Investment Management [Member]
Segment Reporting Information [Line Items]
Net Revenues	19,087	17,332
Operating Expenses	13,857	13,238
Income Before Income from Equity Method Investments and Income Taxes	5,230	4,094
Income from Equity Method Investments	1,637	1,397
Pre-Tax Income	6,867	5,491
Identifiable Segment Assets	$ 126,098	$ 142,122