Segment Information (Net Revenues And Profit By Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014 segment		Sep. 30, 2013
Segment Reporting Information [Line Items]
Number of Reportable Segments					2
Net revenues	$ 758,994		$ 712,731		$ 2,291,373		$ 2,116,014
Segment profit	58,597		87,367		184,903		219,863
Amortization of intangible assets	(33,915)	[1]	(34,716)	[1]	(135,515)	[1]	(104,703)	[1]
Patent litigation charge	(20,727)	[1]	0	[1]	(20,727)	[1]	0	[1]
Restructuring Charges	(3,124)	[1]	0	[1]	(17,285)	[1]	0	[1]
Net interest and other (expense) income, net	(10,374)	[1]	3,438	[1]	(16,897)	[1]	6,009	[1]
Stock-based compensation	(42,449)	[1]	(45,893)	[1]	(128,440)	[1]	(137,306)	[1]
Consolidated income before income taxes	48,222		90,805		168,005		225,872
Enterprise and Service Provider Division [Member]
Segment Reporting Information [Line Items]
Net revenues	593,741		564,552		1,808,209		1,686,411
Segment profit	131,409		134,598		394,536		380,445
SaaS Division [Member]
Segment Reporting Information [Line Items]
Net revenues	165,253		148,179		483,164		429,603
Segment profit	$ 27,402		$ 33,378		$ 92,333		$ 81,427

[1] Represents expenses presented to management on a consolidated basis only and not allocated to the operating segments.