Collaborative Arrangement - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue	$ 26,106,000	$ 34,995,000	$ 49,109,000	$ 57,292,000
Abbott Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement payment received			60,800,000
Total revenue	1,400,000	12,500,000	2,600,000	13,800,000
Collaboration revenue recognized included in balance at beginning of period			2,600,000	$ 3,000,000.0
Upfront and milestone fee payment included in deferred revenue	12,300,000		12,300,000					$ 14,900,000
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		$ 30,000,000