Condensed Consolidated Statements of Changes in Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A 12% convertible preferred stock	Series B-1 12% convertible preferred stock	Series B-2 12% convertible preferred stock	Series B-3 8% convertible preferred stock	Series C super dividend redeemable convertible preferred stock dividend	Series A 12% convertible preferred stock	Series A 12% convertible preferred stock Series A Convertible Preferred Stock [Member]	Series B-1 12% convertible preferred stock	Series B-2 12% convertible preferred stock	Series B-3 8% convertible preferred stock	Common Stock [Member]	Common Stock [Member] Series A 12% convertible preferred stock	Common Stock [Member] Series B-1 12% convertible preferred stock	Common Stock [Member] Series B-2 12% convertible preferred stock	Common Stock [Member] Series B-3 8% convertible preferred stock	Common Stock [Member] Series C super dividend redeemable convertible preferred stock dividend	Common Stock [Member] Series A Convertible Preferred Stock [Member]	Common Stock [Member] Series B Convertible Preferred Stock [Member]	Additional Paid-In Capital	Additional Paid-In Capital Series A 12% convertible preferred stock	Additional Paid-In Capital Series B-1 12% convertible preferred stock	Additional Paid-In Capital Series B-2 12% convertible preferred stock	Additional Paid-In Capital Series B-3 8% convertible preferred stock	Additional Paid-In Capital Series C super dividend redeemable convertible preferred stock dividend	Additional Paid-In Capital Series A Convertible Preferred Stock [Member]	Additional Paid-In Capital Series B Convertible Preferred Stock [Member]	Retained Deficit	Retained Deficit Series A 12% convertible preferred stock	Retained Deficit Series B-1 12% convertible preferred stock	Retained Deficit Series B-2 12% convertible preferred stock	Retained Deficit Series B-3 8% convertible preferred stock	Retained Deficit Series C super dividend redeemable convertible preferred stock dividend
Temporary Equity, Balance (in shares) at Dec. 31, 2016						176
Temporary Equity, Balance at Dec. 31, 2016						$ 1,723
Convertible preferred stock dividend
Convertible preferred stock dividend (in shares)
Stockholders' Equity (Deficit), Balance (in shares) at Dec. 31, 2017							1,377,500		900,000	2,100,000	2,508,000	35,789,388
Stockholders' Equity (Deficit), Balance at Dec. 31, 2017	$ (530)						$ 557		$ 1,761	$ 3,697	$ 1,224	$ 36								$ 173,363								$ (181,168)
Convertible preferred stock dividend									$ (55)	$ (127)	$ (50)										$ 146	$ 155	$ 363	$ 144	$ 107				$ (146)	$ (210)	$ (490)	$ (194)	$ (107)
Convertible preferred stock dividend (in shares)													27,126	27,835	64,948	25,769	20,394
Issuance of common stock	5,603											$ 1								5,602
Issuance of common stock (in shares)												669,714
Issuance of common stock for warrant exercises	6,003											$ 2								6,001
Issuance of common stock for warrant exercises (in shares)												2,455,595
Issuance of common stock for services	12																			12
Issuance of common stock for services (in shares)												2,883
Issuance of common stock for stock option exercises	$ 3,773											$ 2								3,771
Issuance of common stock for stock option exercises ( in shares)	2,098,829											2,098,829
Issuance of common stock from Series A conversion								$ (20)																		$ 20
Issuance of common stock from Series A conversion (in shares)								(50,000)										8,424
Conversion of Series B Convertible Preferred to common								$ (20)																		$ 20
Conversion of Series B Convertible Preferred to common (in shares)								(50,000)										8,424
Temporary Equity, Balance (in shares) at Dec. 31, 2018						176
Net loss	$ (13,900)																											(13,900)
Temporary Equity, Balance at Dec. 31, 2018						$ 1,723
Stock-based compensation expense	4,445																			4,445
Stockholders' Equity (Deficit), Balance (in shares) at Dec. 31, 2018							1,327,500		900,000	2,100,000	2,508,000	41,190,905
Stockholders' Equity (Deficit), Balance at Dec. 31, 2018	5,175						$ 537		$ 1,761	$ 3,697	$ 1,224	$ 41								194,130								(196,215)
Convertible preferred stock dividend		$ (80)	$ (6)	$ (15)	$ (9)	$ (51)															$ 49				$ 53				$ (129)	$ (6)	$ (15)	$ (9)	$ (104)
Convertible preferred stock dividend (in shares)													13,275				14,280
Issuance of common stock	47,819											$ 10								47,809
Issuance of common stock (in shares)												11,150,620
Issuance of common stock for warrant exercises	2,500											$ 1								2,499
Issuance of common stock for warrant exercises (in shares)												585,223
Issuance of common stock for stock option exercises	$ 150																			150
Issuance of common stock for stock option exercises ( in shares)	150,993											150,993
Issuance of common stock from Series A conversion									$ (1,767)	$ (3,697)	$ (1,224)								$ 4								$ 6,678
Issuance of common stock from Series A conversion (in shares)									(900,000)	(2,100,000)	(2,508,000)								3,789,346
Conversion of Series B Convertible Preferred to common									$ (1,767)	$ (3,697)	$ (1,224)								$ 4								$ 6,678
Conversion of Series B Convertible Preferred to common (in shares)									(900,000)	(2,100,000)	(2,508,000)								3,789,346
Warrant modification (Note 5)																				6,622								(6,622)
Temporary Equity, Balance (in shares) at Dec. 31, 2019						176
Net loss	$ (13,294)																											(13,294)
Temporary Equity, Balance at Dec. 31, 2019						$ 1,723
Stock-based compensation expense	1,683																			1,683
Stockholders' Equity (Deficit), Balance (in shares) at Dec. 31, 2019							1,327,500					56,894,642
Stockholders' Equity (Deficit), Balance at Dec. 31, 2019	$ 43,872						$ 537					$ 56								$ 259,673								$ (216,394)