Revenue Recognition (Disaggregation of Revenue by Principal Geographic Area, Based on Customers' Domiciles) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 637,592	$ 620,103	$ 1,263,928	$ 1,196,159
United States
Disaggregation of Revenue [Line Items]
Total revenue	405,998	388,875	802,781	747,163
Europe, the Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenue	123,969	124,840	253,735	246,586
Asia Pacific Region
Disaggregation of Revenue [Line Items]
Total revenue	71,750	64,033	135,262	124,108
Canada
Disaggregation of Revenue [Line Items]
Total revenue	25,357	27,654	49,604	50,878
Latin America
Disaggregation of Revenue [Line Items]
Total revenue	$ 10,518	$ 14,701	$ 22,546	$ 27,424