Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2019	$ 3,191,860	$ 3,362,469
Other comprehensive loss	1,933	3,596
Balance as of March 31, 2019	3,283,217	3,386,258
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2019	(48,912)	(21,930)
Other comprehensive loss	1,933
Balance as of March 31, 2019	(46,979)	$ (18,334)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2019	(51,904)
Other comprehensive loss	502
Balance as of March 31, 2019	(51,402)
Net Unrealized Losses on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2019	2,992
Other comprehensive loss	1,431
Balance as of March 31, 2019	$ 4,423