Segment Reporting (Schedule Of Net Revenues Earned On Major Geographical Areas) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Total net revenues	[1]	$ 1,224,668	$ 1,045,051	$ 3,605,638	$ 3,202,565
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues		1,167,463	979,282	3,415,635	2,982,274
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues		32,945	45,095	113,168	131,855
Canada [Member]
Segment Reporting Information [Line Items]
Total net revenues		9,309	8,364	31,539	37,195
Other [Member]
Segment Reporting Information [Line Items]
Total net revenues		$ 14,951	$ 12,310	$ 45,296	$ 51,241

[1] No individual client accounted for more than 10 percent of total net revenues for the three and nine months ended September 30, 2024 and 2023.