Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (20,293)	$ (18,849)	$ (68,132)	$ (35,130)
Other comprehensive gain:
Net unrealized gain on available-for-sale securities	27	77	178	96
Total comprehensive loss	$ (20,266)	$ (18,772)	$ (67,954)	$ (35,034)

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

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