Net Loss per Share - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net loss	$ (21,960)	$ (16,767)
Weighted-average common shares outstanding:
Basic and Diluted	39,552,277	32,681,661
Net loss per share, Basic and Diluted	$ (0.56)	$ (0.51)

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

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