Segment Information (Revenues By Product Grouping) (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]
Revenue	$ 767,170	$ 732,901	$ 2,427,044	$ 2,200,741
Workspace [Member]
Segment Reporting Information [Line Items]
Revenue	573,342	512,838	1,811,936	1,562,508
Networking [Member]
Segment Reporting Information [Line Items]
Revenue	166,166	188,191	532,169	537,628
Professional Services [Member]
Segment Reporting Information [Line Items]
Revenue	$ 27,662	$ 31,872	$ 82,939	$ 100,605