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Stockholders' Equity - Common Stock (Details) - USD ($)				3 Months Ended					6 Months Ended		13 Months Ended
	Sep. 21, 2018	Jul. 25, 2018	Jun. 01, 2018	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019
Common Stock [Abstract]
Proceeds from sale of common stock, net									$ 1,984,000	$ (200,000)
Common stock issued (in shares)		6,723
Common stock issued, value				$ 64,000	$ 1,873,000		$ (297,000)	$ 27,000
Common Stock [Member]
Common Stock [Abstract]
Common stock issued (in shares)		6,723		5,000	139,855		192	202
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member]
Common Stock [Abstract]
Remaining availability under financing facility				$ 0					0		$ 0
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] | Maximum [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net			$ 6,500,000
Common Stock [Member] | B. Riley FBR [Member] | ATM Program [Member] | Sales Agreement [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net											$ 3,800,000
Common stock issued (in shares)											200,000
Remaining availability under financing facility				0					0		$ 0
Common Stock [Member] | B. Riley FBR [Member] | ATM Program [Member] | Sales Agreement [Member] | Maximum [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net			$ 6,500,000
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net									$ 100,000
Common stock issued (in shares)									5,000
Common stock issued, value	$ 5,000,000
Period exercisable from the date of issuance	24 months
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Securities Purchase Agreement [Member]
Common Stock [Abstract]
Trading Volume of Common Shares	0
Upper Limit on the Price Per Share	$ 0
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Maximum [Member]
Common Stock [Abstract]
Remaining availability under financing facility				$ 100,000					$ 100,000		$ 100,000
Beneficial ownership percentage of common stock outstanding	4.99%
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Maximum [Member] | Single Regular Purchase [Member]
Common Stock [Abstract]
Common stock issued (in shares)	5,000
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Minimum [Member] | Single Regular Purchase [Member]
Common Stock [Abstract]
Common stock issued, value	$ 1,000,000
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Purchase Agreement [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net						$ 300,000
Common stock issued (in shares)						12,802
Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Purchase Agreement [Member] | Maximum [Member]
Common Stock [Abstract]
Floor price of per share	$ 12.50

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