Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Revenues	$ 90,100	$ 54,385	$ 25,427
Operating expenses:
Cost of revenues	61,406	47,426	32,189
Research and development	43,006	35,683	20,347
Selling, general and administrative	103,267	80,126	43,450
Litigation settlement	22,500
Total operating expenses	230,179	163,235	95,986
Loss from operations	(140,079)	(108,850)	(70,559)
Interest income	1,499	3,032	999
Interest expense	(787)	(1,294)	(1,313)
Other income (expense), net	(182)	(265)	(121)
Loss before income taxes	(139,549)	(107,377)	(70,994)
Provision for income taxes	(382)	(292)	(242)
Net loss attributable to common stockholders	(139,931)	(107,669)	(71,236)
Other comprehensive loss:
Change in unrealized gain (loss) on investments	(34)	49
Foreign currency translation adjustment	(60)	45	54
Comprehensive loss	$ (140,025)	$ (107,575)	$ (71,182)
Net loss per share attributable to common stockholders—basic and diluted	$ (3.57)	$ (3.92)	$ (25.51)
Weighted average shares used in computing net loss per share attributable to common stockholders—basic and diluted	39,190	27,462	2,793