Convertible Preferred Stock and Stockholders' Equity (Details) (USD $)	12 Months Ended	0 Months Ended		1 Months Ended	0 Months Ended
	Dec. 31, 2013	Apr. 19, 2013	Feb. 28, 2013	Feb. 28, 2013	Jul. 02, 2013	May 29, 2013	Apr. 28, 2008	Jan. 31, 2012	Nov. 30, 2012
Convertible preferred stock and stockholders' deficit
Proceeds from issuance of preferred stock, net of issuance costs	$ 16,824,000
Pfizer note
Convertible preferred stock and stockholders' deficit
Interest rate (as a percent)							8.931%
Aggregate principal amount							5,000,000
Outstanding principal amount						7,800,000
Short term convertible notes issued January 2012
Convertible preferred stock and stockholders' deficit
Interest rate (as a percent)								10.00%
Aggregate principal amount								6,000,000
Short term convertible notes issued September and November 2012
Convertible preferred stock and stockholders' deficit
Interest rate (as a percent)									10.00%
Aggregate principal amount									9,700,000
Common stock | Warrant
Convertible preferred stock and stockholders' deficit
Share price of preferred stock (in dollars per share)					6.99
Series A preferred stock
Convertible preferred stock and stockholders' deficit
Conversion of convertible promissory notes into Series A preferred stock (in shares)	16,623,092
Preferred stock, shares authorized		17,000,000
Share price of preferred stock (in dollars per share)		$ 1.00
Proceeds from issuance of preferred stock, net of issuance costs		16,900,000
Stock issuance costs	(120,000)	100,000
Conversion rate		0.143
Number of shares of convertible preferred stock converted into common stock	(57,598,092)
Series A preferred stock | 10% Convertible promissory notes
Convertible preferred stock and stockholders' deficit
Aggregate principal amount			15,700,000	15,700,000
Accrued interest			900,000	900,000
Conversion of convertible promissory notes into Series A preferred stock (in shares)			16,623,092	16,623,092
Conversion price (in dollars per share)			$ 1.00	$ 1.00
Conversion rate			0.143	0.143
Series A-1 preferred stock
Convertible preferred stock and stockholders' deficit
Conversion of convertible promissory notes into Series A preferred stock (in shares)	6,750,000
Stock issuance costs	$ 53,000
Number of shares of convertible preferred stock converted into common stock	(6,750,000)
Series A-1 preferred stock | Pfizer note
Convertible preferred stock and stockholders' deficit
Preferred stock, shares authorized						6,750,000
Share price of preferred stock (in dollars per share)						$ 1.1560
Conversion rate						0.143
Number of shares of convertible preferred stock converted into common stock					966,218
Initial Public Offering | Common stock
Convertible preferred stock and stockholders' deficit
Number of shares of convertible preferred stock converted into common stock					9,210,999
Initial Public Offering | Series A preferred stock
Convertible preferred stock and stockholders' deficit
Number of shares of convertible preferred stock converted into common stock					8,244,781
Initial Public Offering | Series A-1 preferred stock
Convertible preferred stock and stockholders' deficit
Number of shares of convertible preferred stock converted into common stock					966,218