The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 1,700	$ 1,700	$ 1,700
Amortization of license agreements in 2022	1,700
Amortization of license agreements in 2023	1,700
Amortization of license agreements in 2024	1,700
Amortization of license agreements in 2025	1,700
Amortization of license agreements in 2026	1,700
Amortization of license agreements, thereafter	$ 5,200
Novartis \| Licensing Agreement
Finite Lived Intangible Assets [Line Items]
Amortization period of intangible assets	21 years
Finite-lived intangible assets, accumulated amortization	$ 1,000
Novartis \| Patents
Finite Lived Intangible Assets [Line Items]
Amortization period of intangible assets	14 years
Finite-lived intangible assets, accumulated amortization	$ 10,200