Segment Reporting (Schedule Of Net Revenues Earned On Major Geographical Areas) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total net revenues	[1]	$ 4,348,944	$ 4,391,439	$ 4,737,088
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues		4,095,476	4,125,563	4,332,743
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues		152,125	192,985	239,559
Canada [Member]
Segment Reporting Information [Line Items]
Total net revenues		40,034	29,268	109,285
Other [Member]
Segment Reporting Information [Line Items]
Total net revenues		$ 61,309	$ 43,623	$ 55,501

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2023, 2022, and 2021.