Other Balance Sheet Items (Other Current Assets) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Contingent consideration proceeds	$ 20,400
Prepaid registry fees, current	22,539	$ 21,717
Estimated contingent consideration receivable	0	14,721
Prepaid expenses	24,495	19,818
Accounts Receivable, Net	5,338	1,524
Other Assets, Miscellaneous, Current	2,703	2,750
Other Assets, Current	$ 55,075	$ 60,530