Segment Information (Revenues By Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 690,925	$ 668,736	$ 2,046,829	$ 2,001,496
Operating Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	690,925	668,736	2,046,829	2,001,496
Operating Segments [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	406,322	397,349	1,200,740	1,188,719
Operating Segments [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	213,954	199,837	633,119	611,832
Operating Segments [Member] | APJ [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 70,649	$ 71,550	$ 212,970	$ 200,945