Equity - Issue and Conversion (Details) - USD ($)			1 Months Ended	2 Months Ended		12 Months Ended
	Jul. 17, 2019	May 09, 2018	Dec. 31, 2016	Feb. 26, 2020	Feb. 25, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 07, 2018
Proceeds from issuance of common stock, net of issuance costs							$ 2,476,000	$ 809,000
Series A Warrants
Exercise price	$ 0.33
Expiration term of warrant	5 years
Warrants issued	$ 2,100,000
Expected volatility (as a percent)	95.00%
Risk-free rate (as a percent)	1.90%
Series B Warrants
Exercise price	$ 0.33
Incremental fair value of warrants	$ 300,000
Expected volatility (as a percent)	88.00%
Risk-free rate (as a percent)	1.90%
ATM Agreement
Common stock issued (in shares)					545,000		33,995	0
Aggregate value of securities allowed under agreement			$ 5,000,000
Aggregate securities allowed under agreement (in shares)			10,000,000
Sale price (in dollars per shares)				$ 0.31			$ 0.34
Commission rate (as a percent)			2.00%
Proceeds from issuance of common stock, net of issuance costs				$ 200,000			$ 11,000
Total cost of offering			$ 109,000				0	$ 15,000
Unamortized deferred cost							$ 135,000	136,000
Legal expenses			$ 50,000
LPC Program
Common stock issued (in shares)							2,113,642
Sale price (in dollars per shares)							$ 0.28
Commitment fee							$ 300,000
Amortization of deferred cost							58,000	58,000
Proceeds from issuance of common stock, net of issuance costs							590,000
Total cost of offering	$ 300,000						190,000
Placement agent fee (as a percent)	6.00%
Unamortized deferred cost							$ 376,000	$ 432,000
LPC Program | May 2016 Warrants
Exercise price	$ 0.75
LPC Program | Series A Warrants
Common shares issuable upon exercise	8,653,846
Exercise price	$ 0.35
Aggregate gross proceeds	$ 2,250,000
LPC Program | Series B Warrants
Common shares issuable upon exercise	4,500,000
Number of common shares which can be purchased with each warrant	1
Exercise price	$ 0.35
Registered direct purchase agreement
Common stock issued (in shares)		3,153,808						0
Sale price (in dollars per shares)		$ 0.4122
Gross proceeds from common stock sale		$ 1,300,000
Commitment purchase agreement
Common stock issued (in shares)				825,000
Aggregate value of securities allowed under agreement		$ 10,000,000
Sale price (in dollars per shares)				$ 0.27
Number of shares registered for resale under the Commitment Purchase Agreement									15,222,941
Proceeds from issuance of common stock, net of issuance costs				$ 200,000
Subsequent Event [Member]
Proceeds from issuance of common stock, net of issuance costs						$ 400,000
Common Stock
Common stock issued (in shares)							8,653,846	3,153,808
Common Stock | LPC Program
Common stock issued (in shares)	8,653,846
Share Price	$ 0.26
Common Stock | Maximum | LPC Program | Series A Warrants
Common stock issued (in shares)	8,653,846