Other Assets - Summary of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Schedule of Investments [Line Items]
Other assets	$ 4,125	$ 2,124
ViaCyte, Inc. [Member]
Schedule of Investments [Line Items]
Other assets	479	479
Operating Lease Right-of-Use Assets [Member]
Schedule of Investments [Line Items]
Other assets	1,696
Other Noncurrent Assets [Member]
Schedule of Investments [Line Items]
Other assets	$ 1,950	$ 1,645