Segment Information (Net Revenues And Profit By Segment) (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2016 USD ($) segment	Mar. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment		2
Net revenues		$ 825,678	$ 760,802
Segment profit		110,954	51,732
Stock-based compensation		(42,097)	(34,211)
Restructuring		(46,065)	(33,951)
Separation costs		(14,687)	0
Consolidated income before income taxes		102,547	35,597
Operating Segments [Member] | Enterprise and Service Provider Division [Member]
Segment Reporting Information [Line Items]
Net revenues		658,773	613,125
Segment profit	[1]	200,445	118,456
Operating Segments [Member] | Mobility Apps [Member]
Segment Reporting Information [Line Items]
Net revenues		166,905	147,677
Segment profit	[1]	35,868	28,631
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Amortization and impairment of intangible assets		(22,509)	(28,173)
Stock-based compensation		(42,097)	(34,211)
Restructuring		(46,065)	(33,951)
Separation costs		(14,687)	0
Other		0	982
Net interest and other expense, net		$ (8,408)	$ (16,137)

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