Segment Information (Revenues By Geographic Location) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 750,819	$ 672,899
Enterprise and Service Provider Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	593,687	535,333
Enterprise and Service Provider Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	323,393	296,434
Enterprise and Service Provider Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	200,628	174,402
Enterprise and Service Provider Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	69,666	64,497
SaaS Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	157,132	137,566
SaaS Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	130,672	116,230
SaaS Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	21,180	16,743
SaaS Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 5,280	$ 4,593