STATEMENTS OF CONVERTIBLE PREFERRED SHARES AND STOCKHOLDERS' EQUITY (DEFICIT) - (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares
Series C Preferred Stock
Settlement of preferred stock obligation	$ 2,278
Preferred Stock | Series C Preferred Stock
Issued at | $ / shares	$ 1.55
Issuance costs	$ 65
Settlement of preferred stock obligation	$ 2,278
Preferred Stock | Series D Preferred Stock
Issued at | $ / shares	$ 2.35
Issuance costs	$ 255