Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands		Preferred Class A [Member] Common Stock [Member]	Preferred Class A [Member] Preferred Stock [Member]	Preferred Class A [Member] Additional Paid-in Capital [Member]	Preferred Class A [Member] Retained Earnings [Member]	Preferred Class A [Member]	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2018							24,654,911	0
Balance at Dec. 31, 2018							$ 247	$ 0	$ 383,521	$ (470,008)	$ (86,240)
Issuance of shares (in shares)							1,863,072	0
Issuance of shares pursuant to ATM offerings							$ 19	$ 0	19,376	0	19,395
Stock Issued During Period, Shares, Conversion of Convertible Securities (in shares)							1,918,444	0
Issuance of shares pursuant to bond conversion							$ 19	$ 0	12,809	0	12,828
Reclassification of warrant liability to additional paid-in capital(1)	[1]						0	0	2,896	(2,031)	865
Impact of warrant down-round feature							$ 0	$ 0	30	(30)	0
Stock-based compensation expense (in shares)							44,140	0
Stock-based compensation expense							$ 0	$ 0	562	0	562
Net loss and comprehensive loss							$ 0		0	(29,528)	(29,528)
Balance (in shares) at Dec. 31, 2019							28,480,567	0
Balance at Dec. 31, 2019							$ 285	$ 0	419,194	(501,597)	(82,118)
Issuance of shares (in shares)		0	10,000				1,508,013	0
Issuance of shares pursuant to ATM offerings		$ 0	$ 1	$ 39,735	$ 0	$ 39,736	$ 15	$ 0	14,752	0	14,767
Issuance of shares pursuant to bond conversion							57	0	38,843	0	38,900
Reclassification of warrant liability to additional paid-in capital(1)							$ 0	$ 0	(865)	0	(865)
Stock-based compensation expense (in shares)							147,376	0
Stock-based compensation expense							$ 1	$ 0	2,095	0	2,096
Net loss and comprehensive loss							$ 0	$ 0	0	(37,817)	(37,817)
Issuance of shares pursuant to bond conversion (in shares)							5,766,337	0
Conversion of Stock, Shares Issued (in shares)							1,000,068
Conversion of preferred shares to common shares							$ 10			0	0
Conversion of preferred shares to common shares (in shares)								(2,469)
Conversion of preferred shares to common shares								$ 0
Conversion of preferred shares to common shares, APIC impact									(10)
Balance (in shares) at Dec. 31, 2020							36,902,361	7,531
Balance at Dec. 31, 2020							$ 368	$ 1	$ 513,744	$ (539,414)	$ (25,301)

[1] A cumulative effect adjustment of $2,031 thousand was recognized as of January 1, 2019, upon adoption of ASU 2017-11.