Segment Information (Revenues By Geographic Location) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 781,560	$ 730,384	$ 1,532,379	$ 1,403,283
Enterprise and Service Provider Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	620,781	586,526	1,214,468	1,121,859
Enterprise and Service Provider Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	335,593	322,911	658,986	619,345
Enterprise and Service Provider Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	207,069	191,015	407,697	365,417
Enterprise and Service Provider Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	78,119	72,600	147,785	137,097
SaaS Division [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	160,779	143,858	317,911	281,424
SaaS Division [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	132,877	120,680	263,549	236,910
SaaS Division [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	22,193	18,001	43,373	34,744
SaaS Division [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 5,709	$ 5,177	$ 10,989	$ 9,770