Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 1,714,313	$ 1,046,571	$ 54,653
Amortization of license agreements in 2017	1,700,429
Amortization of license agreements in 2018	1,700,429
Amortization of license agreements in 2019	1,700,429
Amortization of license agreements in 2020	1,700,429
Amortization of license agreements in 2021	1,700,429
Amortization of license agreements in 2022	1,700,429
Amortization of license agreements, thereafter	$ 11,962,294
Novartis | Licensing Agreements
Finite Lived Intangible Assets [Line Items]
Amortization period of intangible assets	21 years
Finite-lived intangible assets, accumulated amortization	$ 234,975
Novartis | Patents
Finite Lived Intangible Assets [Line Items]
Amortization period of intangible assets	14 years
Finite-lived intangible assets, accumulated amortization	$ 2,457,371
Roche RNAi | Licensing Agreements
Finite Lived Intangible Assets [Line Items]
Amortization period of intangible assets	4 years
Finite-lived intangible assets, accumulated amortization	$ 230,000