Acquisitions - Summary of Purchase Consideration (Detail) (USD $)	6 Months Ended	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Apr. 30, 2015
Asset Acquisition [Line Items]
Cash payment for acquisition	$ 7,000,000
Novartis
Asset Acquisition [Line Items]
Cash payment for acquisition		10,000,000	7,000,000
Value of Shares Issued to Novartis during the three months ended March 31, 2015		25,000,000
Total purchase consideration		35,000,000
Novartis | Subsequent Event
Asset Acquisition [Line Items]
Cash payment for acquisition				$ 3,000,000