Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (504,080)	$ (244,614)	$ (194,375)
Other comprehensive loss:
Foreign currency translation adjustments	553	(2,196)	(102)
Net unrealized gain (loss) on available-for-sale investments	30	(180)	251
Comprehensive loss	$ (503,497)	$ (246,990)	$ (194,226)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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