CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (121,559)	$ (83,217)	$ (61,422)
Unrealized gains (losses) on investments, net of tax	(337)	75	(75)
Currency translation adjustment	(93)	(21)	0
Comprehensive loss	$ (121,989)	$ (83,163)	$ (61,497)

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

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