Convertible Preferred Stock - Additional Information (Details) - USD ($) $ in Thousands		9 Months Ended
	Apr. 20, 2015	Sep. 30, 2015
Private Placement
Class Of Stock [Line Items]
Issuance of stock		$ 25,000
Private Placement | Common Stock
Class Of Stock [Line Items]
Issuance of stock , Shares		1,470,588
Novartis Agreement | Series E Convertible Preferred Stock
Class Of Stock [Line Items]
Issuance of stock , Shares		2,361,029
Issuance of stock		$ 25,000
Novartis Agreement | Common Stock
Class Of Stock [Line Items]
Common stock, conversion basis		1,699,940
Novartis Agreement | Private Placement
Class Of Stock [Line Items]
Issuance of stock	$ 25,000
Novartis Agreement | Private Placement | Common Stock
Class Of Stock [Line Items]
Issuance of stock , Shares	1,470,588
Issuance of stock	$ 25,000