Condensed Consolidated Statements of Preferred Stock and Stockholders’ Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2018		0	31,825,769
Beginning balance at Dec. 31, 2018	$ 136,949	$ 0	$ 32	$ 250,316	$ (18)	$ (113,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (in shares)			23,345
Vesting of restricted common stock	7			7
Exercise of stock options (in shares)			181,521
Exercise of stock options	257			257
Stock-based compensation expense	1,953			1,953
Unrealized gain on investments	16				16
Net loss	(20,299)					(20,299)
Ending balance (in shares) at Mar. 31, 2019		0	32,030,635
Ending balance at Mar. 31, 2019	118,883	$ 0	$ 32	252,533	(2)	(133,680)
Beginning balance (in shares) at Dec. 31, 2019		0	32,170,605
Beginning balance at Dec. 31, 2019	60,197	$ 0	$ 32	259,018	0	(198,853)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (in shares)			13,390
Vesting of restricted common stock	$ 7			7
Exercise of stock options (in shares)	137,213		137,213
Exercise of stock options	$ 226			226
Stock-based compensation expense	1,955			1,955
Unrealized gain on investments	0
Net loss	(23,041)					(23,041)
Ending balance (in shares) at Mar. 31, 2020		0	32,321,208
Ending balance at Mar. 31, 2020	$ 39,344	$ 0	$ 32	$ 261,206	$ 0	$ (221,894)