Segment Information (Revenues By Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 748,697	$ 742,365	$ 1,467,840	$ 1,439,557
Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	432,281	430,184	833,428	844,184
EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	240,388	234,131	477,201	448,706
APJ [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 76,028	$ 78,050	$ 157,211	$ 146,667