Commitments And Contingencies (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Expiration Date of Registry Agreement	Nov. 30, 2024
Registry fee per transaction	$ 0.25
Uncertain tax positions	23,100,000
Payments for registry fees	36,300,000	$ 34,700,000	$ 33,000,000.0
ICANN SSR Payments	$ 4.0