Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2016 USD ($)
Other Commitments [Line Items]
Facility rent expense	$ 354,400	$ 407,500
Provision for recorded liabilities	0
Future commitments	13,600,000
Commitments expected to be incurred in fiscal 2018	11,100,000
Commitments expected to be incurred beyond fiscal 2018	2,500,000
Technology License Commitments
Other Commitments [Line Items]
Milestone payments	$ 0	$ 0
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	$ 27,000
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
Rental expense including payments of principal and interest on the note payable	$ 182,200
Percentage of increase in annual rental cost excluding principal and interest on the note payable	2.50%
Promissory notes payable amortized term	10 years
Promissory note commencement date	Oct. 01, 2016
Promissory note interest rate	7.10%