Condensed Statement of Convertible Preferred Stock - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019
Increase (Decrease) in Temporary Equity
Balance at beginning of period		$ 35,410
Balance at beginning of period (in shares)		7,095,746
Series A Convertible Preferred Stock
Increase (Decrease) in Temporary Equity
Balance at beginning of period	$ 6,254	$ 6,254
Balance at beginning of period (in shares)	3,093,898	3,093,898
Conversion of convertible preferred stock into common stock upon closing of initial public offering	$ (6,254)
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares)	(3,093,898)
Balance at end of period		$ 6,254
Balance at end of period (in shares)		3,093,898
Series B Convertible Preferred Stock
Increase (Decrease) in Temporary Equity
Balance at beginning of period	$ 32,207	$ 29,156
Balance at beginning of period (in shares)	4,444,773	4,001,848
Issuance of convertible preferred stock for cash, net of issuance costs		$ 3,051
Issuance of convertible preferred stock for cash, net of issuance costs (in shares)		442,925
Conversion of convertible preferred stock into common stock upon closing of initial public offering	$ (32,207)
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares)	(4,444,773)
Balance at end of period		$ 32,207
Balance at end of period (in shares)		4,444,773