Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Dec. 31, 2018 USD ($) ft²	Dec. 31, 2017 USD ($)	Jan. 31, 2019 ft²	Oct. 31, 2018 USD ($)
Other Commitments [Line Items]
Promissory note payable	$ 2,300,000
Facility rent expense	335,000	$ 326,000
Provision for recorded liabilities	0
Future commitments	34,000,000
Commitments expected to be incurred in fiscal 2019	25,000,000
Commitments expected to be incurred beyond fiscal 2019	9,000,000
Technology License Commitments
Other Commitments [Line Items]
Milestone payments	$ 0	$ 0
Subsequent Event | Madison, Wisconsin Research Facility
Other Commitments [Line Items]
Office space leases, in square feet | ft²			13,000
Corporate Headquarters In Pasadena
Other Commitments [Line Items]
Office space leases, in square feet | ft²	8,500
Operating lease expiration month and year	2019-09
Rental expense	$ 28,100
Percentage of increase in annual rental cost	3.00%
Research Facility in Madison
Other Commitments [Line Items]
Office space leases, in square feet | ft²	60,000
Operating lease expiration month and year	2026-09
Primary tenant improvement allowance accounted for as deferred rent	$ 2,100,000
Promissory note payable	2,700,000			$ 2,300,000
Rental expense including payments of principal and interest on the note payable	$ 133,400
Percentage of increase in annual rental cost excluding principal and interest on the note payable	2.50%
Research Facility in Madison | Subsequent Event
Other Commitments [Line Items]
Office space leases, in square feet | ft²			13,000