Statements of Convertible Preferred Stock and Changes in Stockholders' Equity (Deficit), Convertible Preferred Stock - USD ($) $ in Thousands	Series A-1 Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock
Balance at Dec. 31, 2012	$ 898	$ 544	$ 44,928	$ 22,862
Balance (in shares) at Dec. 31, 2012	137,787	66,116	4,510,066	1,578,400
Increase (decrease) in temporary equity
Change
Balance at Dec. 31, 2013	$ 898	$ 544	$ 44,928	$ 22,862
Balance (in shares) at Dec. 31, 2013	137,787	66,116	4,510,066	1,578,400
Increase (decrease) in temporary equity
Conversion of preferred stock to common stock	$ (898)	$ (544)	$ (44,928)	$ (22,862)
Conversion of preferred stock to common stock	(137,787)	(66,116)	(4,510,066)	(1,578,400)
Balance at Dec. 31, 2014
Balance (in shares) at Dec. 31, 2014