Segment Information (Net Revenues And Profit By Segment) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues		$ 908,356	$ 841,251	$ 842,980	$ 825,678	$ 904,763	$ 813,270	$ 796,759	$ 760,802	$ 3,418,265	$ 3,275,594	$ 3,142,856
Segment profit		$ 231,290	$ 153,827	$ 153,087	$ 110,954	$ 112,406	$ 63,798	$ 122,149	$ 51,732	649,158	350,085	302,311
Amortization and impairment of intangible assets	[1]									(89,592)	(239,915)	(192,325)
Stock-based compensation	[1]									(184,788)	(147,368)	(169,287)
Restructuring	[1]									(71,122)	(100,411)	(20,424)
Separation costs	[1]									(56,624)	(6,352)	0
Patent litigation charge	[1]									0	0	(20,727)
Net interest and other expense	[1]									(32,395)	(38,208)	(26,605)
Consolidated income before income taxes										616,764	311,877	275,706
Enterprise and Service Provider
Segment Reporting Information [Line Items]
Net revenues										2,736,080	2,646,154	2,563,064
Segment profit										891,187	702,229	558,069
Restructuring										(67,401)	(96,952)	(14,092)
GoTo Business Division
Segment Reporting Information [Line Items]
Net revenues										682,185	629,440	579,792
Segment profit										160,098	140,920	147,005
Restructuring										(3,721)	(3,459)	(6,332)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Other	[1]									$ 0	$ 982	$ 0

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