CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at beginning at Dec. 31, 2018	$ 26	$ 213,453	$ (8)	$ (106,848)	$ 106,623
Balance at beginning (in shares) at Dec. 31, 2018	26,217,701
Increase (decrease) in Stockholders' Equity
Unrealized gain on marketable securities			24		24
Restricted shares forfeited during the period (in shares)	(2,237)
Exercise of stock options		13			13
Exercise of stock options (in shares)	1,983
Equity-based compensation expense		1,618			1,618
Net Loss				(10,755)	(10,755)
Balance at end at Mar. 31, 2019	$ 26	215,084	16	(117,603)	97,523
Balance at end (in shares) at Mar. 31, 2019	26,217,447
Balance at beginning at Dec. 31, 2019	$ 30	270,682	37	(157,848)	112,901
Balance at beginning (in shares) at Dec. 31, 2019	29,792,922
Increase (decrease) in Stockholders' Equity
Unrealized gain on marketable securities			197		197
Exercise of stock options		405			405
Exercise of stock options (in shares)	40,252
Equity-based compensation expense		2,214			2,214
Net Loss				(17,070)	(17,070)
Balance at end at Mar. 31, 2020	$ 30	$ 273,301	$ 234	$ (174,918)	$ 98,647
Balance at end (in shares) at Mar. 31, 2020	29,833,174