Equity - Issue and Conversion (Details) - USD ($)								1 Months Ended		3 Months Ended	12 Months Ended
	Feb. 15, 2021	Jul. 21, 2020	Apr. 22, 2020	Apr. 20, 2020	Apr. 09, 2020	Jul. 17, 2019	May 09, 2018	Jul. 31, 2019	Dec. 31, 2016	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2021	Jul. 19, 2019
Proceeds from issuance of common stock, net of issuance costs											$ 14,599,000	$ 2,476,000
Warrants Series A and B
Exercise price				$ 0.24
Warrants issued				$ 1,900,000
Expected volatility (as a percent)				95.00%
Risk-free rate (as a percent)				0.41%
Series A Warrants
Warrants Exercise Period						6 months					6 months
Exercise price						$ 0.33
Warrants issued						$ 2,100,000
Expected volatility (as a percent)						95.00%
Risk-free rate (as a percent)						1.90%
Expiration term of warrant						5 years
Series B Warrants
Common shares issuable upon exercise										4,500,000	4,500,000
Exercise price						$ 0.33				$ 0.35	$ 0.35
Expected volatility (as a percent)						88.00%
Risk-free rate (as a percent)						1.90%
Incremental fair value of warrants						$ 300,000
Subsequent Event | Series A Warrants
Exercise price													$ 0.30
Subsequent Event | Series B Warrants
Exercise price													$ 0.35
Private Placement
Total cost of offering				$ 334,000
Placement agent fee (as a percent)				6.00%
Private Placement | Warrants Series A and B
Share Price				$ 0.30
Aggregate gross proceeds of warrants				$ 3,000,000
Private Placement | Series A Warrants
Number of common shares which can be purchased with each warrant						1
ATM Agreement
Proceeds from issuance of common stock, net of issuance costs											$ 223,000	$ 11,000
Common stock issued (in shares)											823,452	33,995
Aggregate value of securities allowed under agreement									$ 5,000,000
Sale price (in dollars per shares)										$ 0.28	$ 0.28	$ 0.34
Amortization of deferred cost											$ 8,000	$ 1,000
Unamortized deferred cost										$ 127,000	$ 127,000	135,000
Aggregate securities allowed under agreement (in shares)									10,000,000
Commission rate (as a percent)									2.00%
common shares available for issuance										2,200,000	2,200,000
ATM Agreement | Subsequent Event
Purchase price	$ 0.97
Proceeds from issuance of common stock, net of issuance costs	$ 1,800,000
Common stock issued (in shares)	1,856,960
Commission rate (as a percent)	2.00%
Gross proceeds from common stock sale	$ 37,000
Commission payment	$ 6,000
LPC Program [Member]
Total cost of offering						$ 300,000
Proceeds from issuance of common stock, net of issuance costs											$ 216,000	$ 590,000
Common stock issued (in shares)											900,000	2,113,642
Placement agent fee (as a percent)						6.00%
Sale price (in dollars per shares)										$ 0.27	$ 0.27	$ 0.28
Amortization of deferred cost											$ 24,000	$ 58,000
Unamortized deferred cost										$ 352,000	$ 352,000	$ 376,000
common shares available for issuance										12,200,000	12,200,000
LPC Program [Member] | May 2016 Warrants
Exercise price						$ 0.75
LPC Program [Member] | Series A Warrants
Common shares issuable upon exercise						8,653,846
Aggregate gross proceeds of warrants						$ 2,250,000
Exercise price						$ 0.35
LPC Program [Member] | Series B Warrants
Common shares issuable upon exercise						4,500,000
Exercise price						$ 0.35
Number of common shares which can be purchased with each warrant														1
Commitment purchase agreement
Common shares issuable upon exercise							3,153,808
Exercise price							$ 0.4122
Aggregate value of securities allowed under agreement							$ 10,000,000
Gross proceeds from common stock sale							$ 1,300,000
Firm Commitment Offering
Number of shares to purchase in agreement		17,857,143
Purchase price		$ 0.42
Percentage of underwriting discount		6.00%
Total cost of offering		$ 155,000
Proceeds from issuance of common stock, net of issuance costs		$ 8,000,000
Over-Allotment Option
Number of shares to purchase in agreement		2,678,571
Minimum | Private Placement
Warrants Exercise Period			6 months
Maximum | Private Placement
Warrants Exercise Period			5 years
Common Stock | Series B Warrants
Proceeds from issuance of common stock, net of issuance costs										$ 2,600,000
Common Stock | Private Placement
Common stock issued (in shares)				15,000,000							15,000,000
Share Price				$ 0.20
Common shares issuable upon exercise				11,250,000
Common Stock | Private Placement | Series A Warrants
Common shares issuable upon exercise				7,500,000						5,000,000	5,000,000
Common Stock | Private Placement | Series B Warrants
Common shares issuable upon exercise				3,750,000						3,500,000	3,500,000
Exercise price			$ 0.26							$ 0.30	$ 0.30
Common Stock | Subscription Agreement
Common stock issued (in shares)											4,719,207
Common Stock | LPC Program [Member]
Common stock issued (in shares)						8,653,846		8,653,846
Share Price						$ 0.26
Common Stock | Registered direct purchase agreement
Common stock issued (in shares)												8,653,846
Common Stock | Firm Commitment Offering
Common stock issued (in shares)											20,535,714
Common Stock | Maximum | LPC Program [Member] | Series A Warrants
Common stock issued (in shares)						8,653,846
Barrick | Subscription Agreement
Number of shares to purchase in agreement					4,719,207
Purchase price					$ 0.2119
Proceeds from issuance of common stock, net of issuance costs					$ 900,000