Collaborative Arrangement - Additional Information (Detail) - Abbott [Member] - USD ($)		3 Months Ended	6 Months Ended
	Feb. 26, 2018	Mar. 31, 2018	Mar. 31, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee received	$ 25,000,000	$ 25,000,000
Collaboration revenue recognized		$ 500,000	$ 500,000
Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement additional potential milestone payments receivable	$ 67,000,000