Segment Information (Revenues By Geographic Location) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 758,994	$ 712,731	$ 2,291,373	$ 2,116,014
Enterprise and Service Provider Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	593,741	564,552	1,808,209	1,686,411
Enterprise and Service Provider Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	318,180	306,050	977,166	925,395
Enterprise and Service Provider Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	202,557	188,220	610,254	553,637
Enterprise and Service Provider Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	73,004	70,282	220,789	207,379
SaaS Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	165,253	148,179	483,164	429,603
SaaS Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	137,031	124,044	400,580	360,954
SaaS Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	22,407	18,522	65,780	53,266
SaaS Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 5,815	$ 5,613	$ 16,804	$ 15,383