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, 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]
Unrealized gain on investments	19
Net loss	(41,240)
Ending balance (in shares) at Jun. 30, 2019		0	32,045,706
Ending balance at Jun. 30, 2019	100,088	$ 0	$ 32	254,676	1	(154,621)
Beginning balance (in shares) at Mar. 31, 2019		0	32,030,635
Beginning balance at Mar. 31, 2019	118,883	$ 0	$ 32	252,533	(2)	(133,680)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (in shares)			13,692
Vesting of restricted common stock	7			7
Exercise of stock options (in shares)			1,379
Exercise of stock options	1			1
Stock-based compensation expense	2,135			2,135
Unrealized gain on investments	3				3
Net loss	(20,941)					(20,941)
Ending balance (in shares) at Jun. 30, 2019		0	32,045,706
Ending balance at Jun. 30, 2019	100,088	$ 0	$ 32	254,676	1	(154,621)
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
Exercise of stock options	226			226
Stock-based compensation expense	1,955			1,955
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)
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]
Exercise of stock options (in shares)	141,157
Unrealized gain on investments	$ 0
Net loss	(43,693)
Ending balance (in shares) at Jun. 30, 2020		0	46,136,643
Ending balance at Jun. 30, 2020	69,206	$ 0	$ 46	311,706	0	(242,546)
Beginning balance (in shares) at Mar. 31, 2020		0	32,321,208
Beginning balance at Mar. 31, 2020	39,344	$ 0	$ 32	261,206	0	(221,894)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in public offering, net of fees (in shares)			13,800,000
Issuance of common stock in public offering, net of fees	48,407		$ 14	48,393
Vesting of restricted common stock (in shares)			11,491
Vesting of restricted common stock	5			5
Exercise of stock options (in shares)			3,944
Exercise of stock options	9			9
Stock-based compensation expense	2,093			2,093
Unrealized gain on investments	0
Net loss	(20,652)					(20,652)
Ending balance (in shares) at Jun. 30, 2020		0	46,136,643
Ending balance at Jun. 30, 2020	$ 69,206	$ 0	$ 46	$ 311,706	$ 0	$ (242,546)