Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Total
Stockholders' Equity, Beginning Balance at Dec. 31, 2019	$ 37	$ 412,227	$ (104)	$ (312,648)	$ 99,512
Shares, Outstanding, Beginning Balance at Dec. 31, 2019	36,865,116
Exercises of vested stock options		34			34
Exercises of vested stock options (in shares)	3,035
Vesting of restricted stock units (in shares)	108,600
Stock based compensation expense		3,949			3,949
Unrealized gain on available for-sale securities, net of tax			525		525
Net loss				(24,263)	(24,263)
Stockholders' Equity, Ending Balance at Mar. 31, 2020	$ 37	416,210	421	(336,911)	79,757
Shares, Outstanding, Ending Balance at Mar. 31, 2020	36,976,751
Stockholders' Equity, Beginning Balance at Dec. 31, 2020	$ 37	430,324	(134)	(275,907)	154,320
Shares, Outstanding, Beginning Balance at Dec. 31, 2020	37,368,027
Exercises of vested stock options	$ 1	27			$ 28
Exercises of vested stock options (in shares)	3,811				3,811
Vesting of restricted stock units (in shares)	184,217
Stock based compensation expense		3,498			$ 3,498
Unrealized gain on available for-sale securities, net of tax			11		11
Net loss				(21,649)	(21,649)
Stockholders' Equity, Ending Balance at Mar. 31, 2021	$ 38	$ 433,849	$ (123)	$ (297,556)	$ 136,208
Shares, Outstanding, Ending Balance at Mar. 31, 2021	37,556,055