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Liquidity and Going Concern - Additional Information (Details) - USD ($)	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Apr. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Liquidity [Line Items]
Net loss		$ 1,087,000	$ 3,150,000
Accumulated deficit		(426,357,000)			$ (425,270,000)
Net cash used in operating activities		$ (1,502,000)	(3,270,000)
Substantial doubt about going concern, description		These factors raise substantial doubt about the Company?s ability to continue as a going concern.
Stockholders' equity (deficit)		$ 85,000	3,857,000		1,160,000		$ 5,225,000
Excercise price		$ 2.25
Warrant liability		$ 5,262,000			$ 6,929,000
Change in fair value of warrants		(1,667,000)	$ (210,000)
Scenario Forecast [Member]
Liquidity [Line Items]
Change in fair value of warrants	$ 700,000
Subsequent Event [Member]
Liquidity [Line Items]
Warrant liability				$ 4,200,000
Nasdaq Stock Market LLC [Member]
Liquidity [Line Items]
Stockholders' equity (deficit)		(85,000)				$ 6,300,000
Minimum stockholders equity requirement		$ 2,500,000

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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