Commitments and Contingencies - Additional Information (Detail)		12 Months Ended
	Jan. 08, 2016 USD ($) ft² Option	Sep. 30, 2016 USD ($) ft²	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Other Commitments [Line Items]
Facility rent expense		$ 839,000	$ 744,000	$ 554,000
Provision for recorded liabilities		0
Future commitments		10,400,000
Commitments expected to be incurred in fiscal 2017		10,400,000
Commitments expected to be incurred beyond fiscal 2017		0
Technology License Commitments
Other Commitments [Line Items]
Milestone payments		3,000,000	$ 1,000,000	$ 1,000,000
Corporate Headquarters In Pasadena
Other Commitments [Line Items]
Rental expense		$ 26,000
Operating lease expiration month and year		2019-09
Percentage of increase in annual rental cost		3.00%
Office space leases, in square feet | ft²		8,500
Research Facility in Madison
Other Commitments [Line Items]
Rental expense		$ 26,000
Office space leases, in square feet | ft²	60,000
Operating lease initial term	10 years
Operating lease commencement date	Jan. 01, 2016
Operating lease available for occupancy month and year		2016-10
Operating lease payments during initial term	$ 15,200,000
Estimated payment for real estate taxes, operating expenses and common area maintenance expenses	600,000
Amount paid or accrued for leasehold improvements, net of tenant improvement allowances		$ 7,000,000
Primary tenant improvement allowance accounted for as deferred rent	2,100,000
Secondary tenant improvement allowance accounted for as note payable	$ 2,700,000
Number of renewal options | Option	2
Operating leases renewal term	5 years
Other rental expenses including common area maintenance and real estate taxes		20,000
Utilities costs per month		18,000
Monthly payments under capital lease		19,000
Total Monthly Facility Expense - Madison facility		83,000
Promissory note payable		$ 2,700,000
Promissory notes payable amortized term		10 years
Promissory note commencement date		Oct. 01, 2016
Promissory note interest rate		7.10%
Research Facility in Middleton
Other Commitments [Line Items]
Rental expense		$ 14,000
Operating lease expiration month and year		2016-12
Other rental expenses including common area maintenance and real estate taxes		$ 4,000