Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Convertible preferred stock (Series A and B), par value	$ 0.0001	$ 0.0001
Convertible preferred stock (Series A and B), shares authorized	44,683,824	45,000,000
Convertible preferred stock (Series A and B), shares issued	44,683,824	10,000,000
Convertible preferred stock (Series A and B), shares outstanding	44,683,824	10,000,000
Convertible preferred stock (Series A and B), aggregate liquidation preference	$ 89,500	$ 10,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	68,000,000	65,700,000
Common stock, shares issued	4,105,178	4,056,818
Common stock, shares outstanding	4,105,178	4,056,818