Acquisitions - Summary of Estimated Fair Values at Date of Acquisition (Detail) (USD $)	3 Months Ended	6 Months Ended
	Mar. 31, 2015	Mar. 31, 2015
Asset Acquisition [Line Items]
Assets acquired		$ 24,857,214
Acquired in-process research and development	10,142,786	10,142,786
Novartis
Asset Acquisition [Line Items]
Assets acquired	35,000,000
Acquired in-process research and development	10,142,786
Novartis | Patents [Member]
Asset Acquisition [Line Items]
Assets acquired	21,728,334
Novartis | License [Member]
Asset Acquisition [Line Items]
Assets acquired	$ 3,128,880