Net Loss Per Share - Computation of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net loss	$ (108,470)	$ (102,773)	$ (105,386)
Net loss available to ordinary shareholders - basic and diluted	$ (108,470)	$ (102,773)	$ (105,386)
Denominator:
Weighted-average shares outstanding - basic and diluted	91,637,966	71,610,035	54,874,391
Loss per share - basic and diluted	$ (1.18)	$ (1.44)	$ (1.92)