Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		2 Months Ended	3 Months Ended	12 Months Ended
	May 29, 2018	Jul. 31, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Common Stock and Preferred Stock
Convertible preferred stock converted into shares			15,109,950
Increase in common stock authorized (in shares)	90,000,000
Common stock, shares authorized	150,000,000			150,000,000	150,000,000
Preferred stock, shares authorized	10,000,000			10,000,000	10,000,000
Preferred stock, par value	$ 0.001			$ 0.001	$ 0.001
Preferred stock, shares issued				0	0
Preferred stock, shares outstanding				0	0
Sale of common shares (in shares)		3,450,000	6,164,000
Purchase price (in dollars per share)		$ 15.00	$ 14.00
Proceeds from sale of common stock			$ 77,800	$ 48,348	$ 94,935
Warrant to purchase preferred stock converted into warrant to purchase common stock				7,614