Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2018	$ 3,362,469
Other comprehensive gain (loss)	3,596	$ 10,737
Balance as of March 31, 2018	3,386,257
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2018	(21,930)
Balance as of March 31, 2018	(18,334)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2018	(24,319)
Other comprehensive gain (loss)	6,282
Balance as of March 31, 2018	(18,037)
Net Unrealized Gains (Losses) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of January 1, 2018	2,389
Other comprehensive gain (loss)	(2,686)
Balance as of March 31, 2018	$ (297)