Segment Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net Revenues	$ 722,854	$ 662,310
Operating Expenses	513,490	468,095
Other Expenses	0	7
Income Before Income from Equity Method Investments and Income Taxes	209,364	194,208
Income from Equity Method Investments	2,512	3,024
Pre-Tax Income	211,876	197,232
Identifiable Segment Assets	2,938,364	2,725,913	$ 3,802,657
Investment Banking [Member]
Segment Reporting Information [Line Items]
Net Revenues	704,301	647,285
Operating Expenses	500,572	456,526
Other Expenses	0	7
Income Before Income from Equity Method Investments and Income Taxes	203,729	190,752
Income from Equity Method Investments	374	169
Pre-Tax Income	204,103	190,921
Identifiable Segment Assets	2,787,619	2,576,598
Investment Management [Member]
Segment Reporting Information [Line Items]
Net Revenues	18,553	15,025
Operating Expenses	12,918	11,569
Other Expenses	0	0
Income Before Income from Equity Method Investments and Income Taxes	5,635	3,456
Income from Equity Method Investments	2,138	2,855
Pre-Tax Income	7,773	6,311
Identifiable Segment Assets	$ 150,745	$ 149,315