Segment Operating Results - Revenues Derived from Clients by Geographical Areas (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net Revenues	$ 395,039	$ 397,953	$ 1,339,922	$ 1,326,606
United States [Member]
Segment Reporting Information [Line Items]
Net Revenues	285,271	317,203	1,042,248	977,870
Europe And Other [Member]
Segment Reporting Information [Line Items]
Net Revenues	104,197	77,779	284,442	337,207
Latin America [Member]
Segment Reporting Information [Line Items]
Net Revenues	$ 5,571	$ 2,971	$ 13,232	$ 11,529