Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2017	$ 49,474		$ 58,544		$ (9,070)
Beginning Balance, shares at Dec. 31, 2017		10,307,247
Issuance of common stock	10		10
Issuance of common stock, shares		2,368
Stock-based compensation expense	65		65
Net loss	(2,150)				(2,150)
Ending balance at Mar. 31, 2018	47,399		58,619		(11,220)
Ending Balance, shares at Mar. 31, 2018		10,309,615
Beginning balance at Dec. 31, 2017	49,474		58,544		(9,070)
Beginning Balance, shares at Dec. 31, 2017		10,307,247
Unrealized gain (loss) on investments	(2)
Net loss	(4,426)
Ending balance at Jun. 30, 2018	45,272		58,770	$ (2)	(13,496)
Ending Balance, shares at Jun. 30, 2018		10,353,916
Beginning balance at Mar. 31, 2018	47,399		58,619		(11,220)
Beginning Balance, shares at Mar. 31, 2018		10,309,615
Issuance of common stock	4		4
Issuance of common stock, shares		1,875
Stock-based compensation expense	147		147
Stock-based compensation expense, shares		42,426
Unrealized gain (loss) on investments	(2)			(2)
Net loss	(2,276)				(2,276)
Ending balance at Jun. 30, 2018	45,272		58,770	(2)	(13,496)
Ending Balance, shares at Jun. 30, 2018		10,353,916
Beginning balance at Dec. 31, 2018	113,226		133,183	2	(19,959)
Beginning Balance, shares at Dec. 31, 2018		14,428,916
Issuance of common stock	44		44
Issuance of common stock, shares		14,653
Stock-based compensation expense	313		313
Unrealized gain (loss) on investments	14			14
Net loss	(4,111)				(4,111)
Ending balance at Mar. 31, 2019	109,486		133,540	16	(24,070)
Ending Balance, shares at Mar. 31, 2019		14,443,569
Beginning balance at Dec. 31, 2018	113,226		133,183	2	(19,959)
Beginning Balance, shares at Dec. 31, 2018		14,428,916
Unrealized gain (loss) on investments	16
Net loss	(9,459)
Ending balance at Jun. 30, 2019	198,290		227,690	18	(29,418)
Ending Balance, shares at Jun. 30, 2019		16,945,069
Beginning balance at Mar. 31, 2019	109,486		133,540	16	(24,070)
Beginning Balance, shares at Mar. 31, 2019		14,443,569
Issuance of common stock	93,825		93,825
Issuance of common stock, shares		2,501,500
Stock-based compensation expense	325		325
Unrealized gain (loss) on investments	2			2
Net loss	(5,348)				(5,348)
Ending balance at Jun. 30, 2019	$ 198,290		$ 227,690	$ 18	$ (29,418)
Ending Balance, shares at Jun. 30, 2019		16,945,069