Business (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jun. 07, 2019	Jun. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018
Business
Reverse stock split	0.167			0.167
Proceeds from Issuance Initial Public Offering | $			$ 133,633
Underwriting discounts and commissions | $		$ 10,100
Offering expenses | $		2,800
Warrants to purchase (in shares) | shares			49,997
Conversion of redeemable convertible preferred stock to common stock | $		209,700	$ 209,668
Deferred offering cost | $		$ 2,800
Payment of deferred offering cost | $			$ 2,848
IPO
Business
Offering price | $ / shares		$ 17.00
Proceeds from Issuance Initial Public Offering | $		$ 130,800
Class A common stock
Business
Number of shares issued up on conversion | shares		13,314,068
Warrants to purchase (in shares) | shares		62,936
Class A common stock | IPO
Business
Shares issued | shares		6,452,500
Class A common stock | Underwriters option
Business
Shares issued | shares		1,102,500
Class B common stock
Business
Number of shares issued up on conversion | shares		3,934,191
Class B common stock | IPO
Business
Shares issued | shares		2,000,000