Condensed Statements of Redeemable Convertible Preferred Stock, Convertible Preferred Stock and Stockholders' Deficit (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019
Series G Redeemable Convertible Preferred Stock
Convertible preferred stock upon conversion of notes, net of issuance costs		$ 190
Stock issuance costs		3,360
Series G Convertible Preferred Stock
Convertible preferred stock upon conversion of notes, net of issuance costs		$ 355
Series H Redeemable Convertible Preferred Stock
Stock issuance costs	$ 86		$ 166
Series H Convertible Preferred Stock
Stock issuance costs	$ 63		$ 59