Collaborative Arrangement - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue	$ 105,136,000	$ 94,864,000	$ 100,077,000
Abbott Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement payment received	60,800,000
Collaborative arrangement additional potential milestone payments receivable	30,000,000
Total revenue	16,000,000.0	12,000,000.0	13,500,000
Upfront and milestone fee payment included in deferred revenue	14,900,000	15,900,000
Collaboration revenue recognized included in balance at beginning of period	4,700,000	5,000,000.0	8,400,000
Abbott Agreement [Member] | Contract Life to Date [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue	45,900,000
Abbott Agreement [Member] | Upfront Payment [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement payment received				$ 25,000,000
Abbott Agreement [Member] | Milestone Payment [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement payment received	15,000,000	$ 10,800,000	$ 10,000,000
Abbott Agreement [Member] | Maximum [Member] | PMA Milestone [Member] | TRANSCEND Clinical Trial [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement additional potential milestone payments receivable	$ 30,000,000