CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Series A, B, C & C-1 Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2018			589,001
Beginning Balance at Dec. 31, 2018	$ (71,618)		$ 6	$ 0	$ 0	$ (71,624)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	384			384
Net income (loss)	(4,580)					(4,580)
Reduction of redeemable convertible preferred stock to redemption value	10,519					10,519
Ending Balance (in shares) at Mar. 31, 2019			589,001
Ending Balance at Mar. 31, 2019	(65,295)		$ 6	384	0	(65,685)
Beginning Balance (in shares) at Dec. 31, 2018		1,256,466
Beginning Balance at Dec. 31, 2018		$ 58,290
Increase (Decrease) in Temporary Equity [Roll Forward]
Reduction of redeemable convertible preferred stock to redemption value		$ (10,519)
Ending Balance (in shares) at Mar. 31, 2019		1,256,466
Ending Balance at Mar. 31, 2019		$ 47,771
Beginning Balance (in shares) at Dec. 31, 2018			589,001
Beginning Balance at Dec. 31, 2018	(71,618)		$ 6	0	0	(71,624)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized loss on available-for-sale marketable securities	0
Net income (loss)	(8,234)
Ending Balance (in shares) at Jun. 30, 2019			589,001
Ending Balance at Jun. 30, 2019	(68,813)		$ 6	520	0	(69,339)
Beginning Balance (in shares) at Dec. 31, 2018		1,256,466
Beginning Balance at Dec. 31, 2018		$ 58,290
Ending Balance (in shares) at Jun. 30, 2019		1,256,466
Ending Balance at Jun. 30, 2019		$ 47,934
Beginning Balance (in shares) at Mar. 31, 2019			589,001
Beginning Balance at Mar. 31, 2019	(65,295)		$ 6	384	0	(65,685)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	299			299
Unrealized loss on available-for-sale marketable securities	0
Net income (loss)	(3,654)					(3,654)
Accretion of redeemable convertible preferred stock to redemption value	(163)			(163)
Ending Balance (in shares) at Jun. 30, 2019			589,001
Ending Balance at Jun. 30, 2019	$ (68,813)		$ 6	520	0	(69,339)
Beginning Balance (in shares) at Mar. 31, 2019		1,256,466
Beginning Balance at Mar. 31, 2019		$ 47,771
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock to redemption value		$ 163
Ending Balance (in shares) at Jun. 30, 2019		1,256,466
Ending Balance at Jun. 30, 2019		$ 47,934
Beginning Balance (in shares) at Dec. 31, 2019	8,480,968		8,480,968
Beginning Balance at Dec. 31, 2019	$ 7,574		$ 85	92,497	(28)	(84,980)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock purchase warrants, net of issuance costs (in shares)			950,000
Issuance of common stock and common stock purchase warrants, net of issuance costs	1,990		$ 10	1,980
Issuance of common stock upon exercise of warrants (in shares)			221,293
Issuance of common stock upon exercise of warrants	15		$ 2	13
Issuance of common stock upon restricted stock unit settlement, net of shares withheld for taxes (in shares)			19,643
Issuance of common stock upon restricted stock unit settlement, net of shares withheld for taxes	(13)			(13)
Stock based compensation	403			403
Unrealized loss on available-for-sale marketable securities	28				28
Net income (loss)	(4,103)					(4,103)
Ending Balance (in shares) at Mar. 31, 2020			9,671,904
Ending Balance at Mar. 31, 2020	5,894		$ 97	94,880	0	(89,083)
Beginning Balance (in shares) at Dec. 31, 2019		0
Beginning Balance at Dec. 31, 2019		$ 0
Ending Balance (in shares) at Mar. 31, 2020		0
Ending Balance at Mar. 31, 2020		$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of common stock and common stock purchase warrants, issuance costs	$ 10
Beginning Balance (in shares) at Dec. 31, 2019	8,480,968		8,480,968
Beginning Balance at Dec. 31, 2019	$ 7,574		$ 85	92,497	(28)	(84,980)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized loss on available-for-sale marketable securities	28
Net income (loss)	$ (9,222)
Ending Balance (in shares) at Jun. 30, 2020	26,671,573		26,671,573
Ending Balance at Jun. 30, 2020	$ 19,910		$ 267	113,845	0	(94,202)
Beginning Balance (in shares) at Dec. 31, 2019		0
Beginning Balance at Dec. 31, 2019		$ 0
Ending Balance (in shares) at Jun. 30, 2020		0
Ending Balance at Jun. 30, 2020		$ 0
Beginning Balance (in shares) at Mar. 31, 2020			9,671,904
Beginning Balance at Mar. 31, 2020	5,894		$ 97	94,880	0	(89,083)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock purchase warrants, net of issuance costs (in shares)			14,790,133
Issuance of common stock and common stock purchase warrants, net of issuance costs	18,679		$ 148	18,531
Issuance of common stock upon exercise of warrants (in shares)			2,202,863
Issuance of common stock upon exercise of warrants	7		$ 22	(15)
Issuance of common stock upon restricted stock unit settlement, net of shares withheld for taxes (in shares)			6,673
Issuance of common stock upon restricted stock unit settlement, net of shares withheld for taxes	(4)			(4)
Stock based compensation	453			453
Unrealized loss on available-for-sale marketable securities	0
Net income (loss)	$ (5,119)					(5,119)
Ending Balance (in shares) at Jun. 30, 2020	26,671,573		26,671,573
Ending Balance at Jun. 30, 2020	$ 19,910		$ 267	$ 113,845	$ 0	$ (94,202)
Beginning Balance (in shares) at Mar. 31, 2020		0
Beginning Balance at Mar. 31, 2020		$ 0
Ending Balance (in shares) at Jun. 30, 2020		0
Ending Balance at Jun. 30, 2020		$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of common stock and common stock purchase warrants, issuance costs	$ 1,443