Net Loss Per Share - Computation of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss	$ (31,166)	$ (9,778)	$ (64,761)	$ (24,365)
Net loss available to ordinary shareholders - basic and diluted	$ (31,166)	$ (9,778)	$ (64,761)	$ (24,365)
Denominator:
Weighted-average shares outstanding - basic and diluted	29,508,330	20,398,132	27,689,009	18,284,708
Loss per share - basic and diluted	$ (1.06)	$ (0.48)	$ (2.34)	$ (1.33)