Segment Reporting (Schedule Of Operating Information, Segment) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Net revenues		$ 1,059,910	$ 883,300	$ 895,817	$ 913,034	$ 944,251	$ 821,572	$ 800,787	$ 770,420	$ 3,752,061	[1]	$ 3,337,030	[1]	$ 3,024,881	[1]
Income/(loss) before income taxes										651,160		599,138		534,362
Global Wealth Management [Member]
Segment Reporting Information [Line Items]
Net revenues	[1]									2,190,826		2,130,559		1,990,319
Income/(loss) before income taxes										725,884		785,960		737,003
Institutional Group [Member]
Segment Reporting Information [Line Items]
Net revenues	[1]									1,583,147		1,214,017		1,055,495
Income/(loss) before income taxes										325,285		175,670		157,051
Other Segments [Member]
Segment Reporting Information [Line Items]
Net revenues	[1]									(21,912)		(7,546)		(20,933)
Income/(loss) before income taxes										$ (400,009)		$ (362,492)		$ (359,692)

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2020, 2019, and 2018.