Collaborative Arrangement - Additional Information (Detail) - Abbott [Member] - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee received			$ 25,000,000
Collaborative arrangement milestone payment received			10,000,000
Collaboration revenue recognized	$ 1,500,000	$ 1,600,000	2,800,000	$ 4,000,000
Upfront and milestone fee payment included in deferred revenue	14,300,000		14,300,000		$ 17,100,000
Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement additional potential milestone payments receivable	$ 56,000,000		$ 56,000,000