Charge on non-transferable subscription rights.

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- Definition

Gross proceeds from issuance of private placement.

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Number of warrants exercised

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Preferred Stock [Abstract]

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Number of warrants or rights outstanding.

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Amount of expense (income) related to adjustment to fair value of warrant liability.

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- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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Per share decrease in exercise price of warrant. Excludes change due to standard antidilution provision.

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- Definition

Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

+ References

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Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Stockholders' Equity - Warrants (Details) - USD ($)			12 Months Ended
Stockholders' Equity - Warrants (Details) - USD ($)	Jul. 25, 2018	Jul. 17, 2018	Dec. 31, 2020	Dec. 31, 2019	Apr. 30, 2020
Preferred Stock [Abstract]
Warrant exercise price (in dollars per share)			$ 2.25
Warrant liability			$ 7,000	$ 6,929,000
Change in fair value of warrants			(2,400,000)	$ (3,407,000)
Outstanding Warrants [Member]
Preferred Stock [Abstract]
Warrant liability			4,500,000
Change in fair value of warrants			$ 700,000
Series U Warrants [Member]
Preferred Stock [Abstract]
Common stock issued (in shares)			3,450,000
Sale of Stock, Price Per Share			$ 5.00
Warrants expected term			5 years
Representative Warrants [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right			75,000
Warrant exercise price (in dollars per share)			$ 6.25
Warrant exercise price decrease			$ 2.81
Common Stock [Member]
Preferred Stock [Abstract]
Common stock issued (in shares)				184,666
Warrants expected term			5 years
Series C Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Warrant exercise price (in dollars per share)					$ 2.25
Common Class A [Member]
Preferred Stock [Abstract]
Common stock issued (in shares)			289,000
Common Class B [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right			2,711,000
2018 Rights Offering [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right		1
Common stock issued (in shares)	6,723
Gross proceeds from private placement of stock	$ 5,700,000
2018 Rights Offering [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right		1,050
2018 Rights Offering [Member] \| Common Stock and Series B Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Charge on Non Transferable Subscription Rights		$ 0
2018 Rights Offering [Member] \| Series C Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right		20,000
2018 Rights Offering [Member] \| Series C Convertible Preferred Stock [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Warrant exercise price (in dollars per share)		$ 1,000
2018 Rights Offering [Member] \| Common Stock [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right					1
2018 Rights Offering [Member] \| Common Stock [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right					50
Series T Warrants [Member] \| 2018 Rights Offering [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Class of warrant outstanding			3,787,350
Number of warrants exercised			75,747
Series U Warrants [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of securities called by warrant or right			3,447,500
Class of warrant outstanding			3,037,500
Number of warrants exercised			3,037,500