Other Assets - Summary of Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Schedule of Investments [Line Items]
Other assets	$ 4,360	$ 2,124
ViaCyte, Inc. [Member]
Schedule of Investments [Line Items]
Other assets		479
Operating Lease Right-of-Use Assets [Member]
Schedule of Investments [Line Items]
Other assets	2,234
Other Noncurrent Assets [Member]
Schedule of Investments [Line Items]
Other assets	$ 2,126	$ 1,645