Segment Information (Revenues By Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 742,365	$ 693,227	[1]	$ 1,439,557	$ 1,355,904	[1]
Operating Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	742,365	693,227	[2]	1,439,557	1,355,904	[2]
Operating Segments [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	430,184	403,072	[1]	844,184	794,418	[1]
Operating Segments [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	234,131	217,313	[1]	448,706	419,165	[1]
Operating Segments [Member] | APJ [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 78,050	$ 72,842	[1]	$ 146,667	$ 142,321	[1]

[1] As noted above, prior period amounts have not been adjusted under the modified retrospective method. See Note 2 for further information regarding the Company’s adoption of the revenue recognition standard.

[2] Prior period amounts have not been adjusted under the modified retrospective method. See Note 2 for further information regarding the Company’s adoption of the revenue recognition standard.