Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Temporary equity convertible preferred stock issuance costs	$ 225	$ 40
Issuance of common stock in initial public offering net of issuance costs	$ 10,829