CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2018	$ 13	$ 172,988	$ (9)	$ (90,109)	$ 82,883
Balance (in shares) at Dec. 31, 2018	13,124,842
Stock-based compensation expense		578			578
Exercise of stock options		11			11
Exercise of stock options (in shares)	2,286
Unrealized gain on investments held			43		43
Net loss				(12,941)	(12,941)
Balance at Mar. 31, 2019	$ 13	173,577	34	(103,050)	70,574
Balance (in shares) at Mar. 31, 2019	13,127,128
Balance at Dec. 31, 2019	$ 13	176,103		(133,959)	42,157
Balance (in shares) at Dec. 31, 2019	13,291,563
Stock-based compensation expense		785			785
Unrealized gain on investments held			28		28
Net loss				(15,266)	(15,266)
Balance at Mar. 31, 2020	$ 13	$ 176,888	$ 28	$ (149,225)	$ 27,704
Balance (in shares) at Mar. 31, 2020	13,291,563