Basis of Presentation, Use of Estimates, and Recent Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands			9 Months Ended
	Apr. 20, 2015 USD ($) $ / shares shares	Apr. 01, 2015	Sep. 30, 2015 USD ($) shares	Apr. 14, 2015 shares	Dec. 31, 2014 shares
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Reverse split of common stock			On April 1, 2015, the Company effected a 0.72-for-1 reverse split of its common stock. Upon the effectiveness of the reverse stock split, (i) every 1 share of outstanding common stock was combined into 0.72 of a share of common stock, (ii) the number of shares of common stock for which each outstanding option or warrant to purchase common stock is exercisable was proportionally decreased on a 0.72-for-1 basis, (iii) the exercise price of each outstanding option or warrant to purchase common stock was proportionately increased on a 0.72-for-1 basis, and (iv) the conversion ratio for each share of preferred stock which was convertible into the Company’s common stock was proportionately reduced on a 0.72-for-1 basis. All of the outstanding common stock share numbers, warrants to purchase common stock, common stock share prices, common stock exercise prices and per share amounts have been adjusted, on a retroactive basis, to reflect this 0.72-for-1 reverse stock split for all periods presented.
Preferred stock shares authorized			10,000,000	10,000,000	0
Common stock shares authorized			300,000,000	300,000,000	85,000,000
IPO
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock | $			$ 124,193
Private Placement
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock | $			$ 25,000
Novartis Agreement | Private Placement
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock | $	$ 25,000
Common Stock
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Stock split conversion ratio		0.72
Number of common stock issued on conversion of convertible preferred stock			51,822,659
Common Stock | IPO
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock , Shares	8,050,000		8,050,000
Stock price per share | $ / shares	$ 17.00
Proceeds from IPO net of underwriting discount, commission and offering expenses | $	$ 124,200
Issuance of stock | $			$ 1
Number of common stock issued on conversion of convertible preferred stock	51,822,659
Common Stock | Exercise of Underwriters
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock , Shares	1,050,000
Common Stock | Private Placement
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock , Shares			1,470,588
Common Stock | Novartis Agreement | Private Placement
Basis Of Presentation Use Of Estimates And Recent Accounting Policies [Line Items]
Issuance of stock , Shares	1,470,588
Stock price per share | $ / shares	$ 17.00
Issuance of stock | $	$ 25,000