Segment Information (Revenues By Product Grouping) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net revenues		$ 777,857	$ 690,925	$ 693,227	$ 662,677	$ 734,584	$ 668,736	$ 673,987	$ 658,773	$ 2,824,686	$ 2,736,080	$ 2,646,154
Workspace Services revenues
Segment Reporting Information [Line Items]
Net revenues	[1]									1,734,837	1,684,897	1,633,820
Networking revenues
Segment Reporting Information [Line Items]
Net revenues	[1]									790,434	782,875	749,910
Content Collaboration revenues
Segment Reporting Information [Line Items]
Net revenues	[2]									167,115	136,842	106,655
Professional services
Segment Reporting Information [Line Items]
Net revenues	[2]									$ 132,300	$ 131,466	$ 155,769

[1] Workspace Services revenues are primarily comprised of sales from the Company’s application virtualization solutions, which include XenDesktop and XenApp, the Company's enterprise mobility management solutions, which include XenMobile, related license updates and maintenance and support and cloud offerings.

[2] Networking revenues primarily include NetScaler ADC and NetScaler SD-WAN, related license updates and maintenance and support and cloud offerings.