Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($)
Series B Convertible Preferred Stock [Member]
Issuance costs of convertible preferred stock	$ 71
Series C Convertible Preferred Stock [Member]
Issuance costs of convertible preferred stock	187
Series D and D-1 Convertible Preferred Stock [Member]
Issuance costs of convertible preferred stock	$ 168