Segment Reporting (Schedule of Net Revenues Earned on Major Geographical Areas) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Total net revenues	[1]	$ 1,108,126	$ 1,153,136	$ 2,224,653	$ 2,287,925
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues		1,042,369	1,058,541	2,097,471	2,074,436
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues		49,992	58,507	93,856	119,725
Canada [Member]
Segment Reporting Information [Line Items]
Total net revenues		5,933	24,656	13,384	67,012
Other [Member]
Segment Reporting Information [Line Items]
Total net revenues		$ 9,832	$ 11,432	$ 19,942	$ 26,752

[1] No individual client accounted for more than 10 percent of total net revenues for the three and six months ended June 30, 2022 and 2021.