Commitments And Contingencies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 16, 2013 Rate	Nov. 28, 2011	Nov. 22, 2011	Aug. 31, 2007 Rate	Aug. 15, 2007 Rate
Commitments And Contingencies [Line Items]
Rental expenses under operating leases	$ 1,600,000	$ 1,900,000	$ 3,000,000
Number of domain names registered	115,600,000
Uncertain tax positions	210,300,000
Line of Credit Facility, Current Borrowing Capacity	200,000,000					200,000,000
Line of Credit Facility, Amount Borrowed					100,000,000
Principal amount of debt	1,250,000,000	1,250,000,000		750,000,000				1,250,000,000
Convertible debenture, interest rate				4.625%			3.25%	3.25%
Indemnification period (months)	60
Claims threshold amount to trigger indemnification obligation	4,000,000
Percentage of claims to be indemnified	50.00%
Maximum indemnification obligation	50,000,000
Net cash provided by operating activities	600,949,000	579,397,000	537,630,000
ICANN Agreement [Member]
Commitments And Contingencies [Line Items]
Expiration Date of Registry Agreement	November 30, 2018
Registry fee per transaction	0.25
Payments for registry fees	28,400,000	27,900,000	18,700,000
.TV Agreement [Member]
Commitments And Contingencies [Line Items]
renewed agreement fees	$ 4,500,000	$ 4,500,000	$ 4,000,000