Consolidated Statements of Stockholders' Equity (deficit) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive loss	Deficit accumulated during the development stage	Series A convertible preferred stock	Series A convertible preferred stock Convertible preferred stock	Series A convertible preferred stock Common stock	Series A convertible preferred stock Additional paid-in capital	Series B convertible preferred stock	Series B convertible preferred stock Convertible preferred stock	Series B convertible preferred stock Common stock	Series B convertible preferred stock Additional paid-in capital
Balance at Apr. 04, 2011
Increase (decrease) in stockholders' equity
Sale of common stock to founders	$ 1	$ 1
Sale of common stock to founders (in shares)		526,443
Vesting of restricted stock	1	1
Vesting of restricted stock (in shares)		683,309
Issuance of convertible preferred stock, net of issuance costs of $2,246 at 2012 and $101 at 2011	(101)		(101)				6,200
Issuance of convertible preferred stock, net of issuance costs of $2,246 at 2012 and $101 at 2011 (in shares)							6,200,000
Stock-based compensation expense	346		346
Net loss	(2,624)				(2,624)
Balance at Dec. 31, 2011	(2,377)	2	245		(2,624)		6,200
Balance (in shares) at Dec. 31, 2011		1,209,752					6,200,000
Increase (decrease) in stockholders' equity
Vesting of restricted stock	1	1
Vesting of restricted stock (in shares)		674,505
Issuance of convertible preferred stock, net of issuance costs of $2,246 at 2012 and $101 at 2011											34,992
Issuance of convertible preferred stock, net of issuance costs of $2,246 at 2012 and $101 at 2011 (in shares)											6,770,563
Conversion of Series A preferred stock to common stock	6,200	3	6,197
Common stock issued from the Conversion of Series A preferred stock to common stock (in shares)		3,064,753
Conversion of Series B preferred stock to common stock	34,992	7	34,985
Common stock issued from the Conversion of Series A preferred stock to common stock (in shares)		6,770,563
Conversion of preferred stock to common stock						6,200	(6,200)	3	6,197	34,992	(34,992)	7	34,985
Conversion of preferred stock to common stock (in shares)							(6,200,000)	3,064,753			(6,770,563)	6,770,563
Common stock issued in a private placement, net of issuance costs of $898	4,039	1	4,038
Common stock issued in a private placement, net of issuance costs of $898 (in shares)		897,554
Stock options exercised (in shares)		5,792
Stock-based compensation expense	1,382		1,382
Unrealized loss on investments	(6)			(6)
Net loss	(13,510)				(13,510)
Balance at Dec. 31, 2012	$ 30,721	$ 14	$ 46,847	$ (6)	$ (16,134)
Balance (in shares) at Dec. 31, 2012		12,622,919