STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Offering cost for common stock issued in public offering	$ 3,796
Underwriting discount for common stock issued in public offering	6,440
Redeemable Convertible Preferred Stock | Series B-1
Issuance of temporary equity, adjustments to convertible preferred stock liability		$ 1,303
Temporary equity stock issued issuance costs		33
Redeemable Convertible Preferred Stock | Series C
Issuance of temporary equity, adjustments to convertible preferred stock liability		395
Temporary equity stock issued issuance costs	30	$ 298
Redeemable Convertible Preferred Stock | Series D
Temporary equity stock issued issuance costs	$ 255