Net loss per share attributable to common stockholders - Computation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss attributable to common stockholders	$ (60,668)	$ (37,919)	$ (106,231)	$ (70,819)
Denominator:
Weighted average shares used in computing net loss per share, basic (in shares)	53,472	48,709	51,673	47,340
Weighted average shares used in computing net loss per share, diluted (in shares)	53,472	48,709	51,673	47,340
Net loss per share attributable to common stockholders—basic (in usd per share)	$ (1.13)	$ (0.78)	$ (2.06)	$ (1.50)
Net loss per share attributable to common stockholders, diluted (in usd per share)	$ (1.13)	$ (0.78)	$ (2.06)	$ (1.50)