Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 23,108	$ 17,466
Less: Accumulated depreciation and amortization	(12,181)	(9,092)
Property and equipment, net	10,927	8,374
Laboratory and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	13,403	11,110
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	6,623	3,739
Purchased Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,299	1,039
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,303	630
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 480	331
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment		$ 617

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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