Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 3,657,958	$ 3,191,860	$ 3,362,469
Other comprehensive income	24,943	3,768	(26,982)
Ending Balance	4,251,296	3,657,958	3,191,860
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(45,144)	(48,912)	(21,930)
Ending Balance	(20,201)	(45,144)	(48,912)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(52,924)	(51,904)
Other comprehensive income	19,629	(1,020)
Ending Balance	(33,295)	(52,924)	(51,904)
Net Unrealized Gains on Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	7,780	2,992
Other comprehensive income	5,314	4,788
Ending Balance	$ 13,094	$ 7,780	$ 2,992