Segment Information (Revenues By Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 813,270	$ 758,994	$ 2,370,831	$ 2,291,373
Operating Segments [Member] | Enterprise and Service Provider Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	622,513	593,741	1,833,126	1,808,209
Operating Segments [Member] | Enterprise and Service Provider Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	345,417	318,180	1,005,967	977,166
Operating Segments [Member] | Enterprise and Service Provider Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	206,377	202,557	616,558	610,254
Operating Segments [Member] | Enterprise and Service Provider Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	70,719	73,004	210,601	220,789
Operating Segments [Member] | Mobility Apps [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	190,757	165,253	537,705	483,164
Operating Segments [Member] | Mobility Apps [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	160,079	137,031	452,672	400,580
Operating Segments [Member] | Mobility Apps [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	24,480	22,407	67,843	65,780
Operating Segments [Member] | Mobility Apps [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 6,198	$ 5,815	$ 17,190	$ 16,804