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Stockholders' Equity - Common Stock (Details) - USD ($)				3 Months Ended	7 Months Ended	12 Months Ended
	Sep. 21, 2018	Jul. 25, 2018	Jun. 01, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	May 24, 2018	May 23, 2018
Common Stock [Abstract]
Number of shares callable by warrants (in shares)								2,300,000	23,400,000
Proceeds from sale of common stock, net						$ 15,964,000	$ 0
Common stock issued, value						$ 2,208,000	$ 1,624,000
Series U Warrants [Member]
Common 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]
Common Stock [Abstract]
Number of shares callable by warrants (in shares)						75,000
Warrant exercise price (in dollars per share)						$ 6.25
Common Stock [Member]
Common Stock [Abstract]
Common stock issued (in shares)		6,723				184,666	92,169
Warrants expected term						5 years
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]
Common stock issued (in shares)					79,234
Proceeds from sale of common stock, net					$ 1,700,000
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]
Common stock issued (in shares)						32,170
Proceeds from sale of common stock, net						$ 300,000
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] | Purchase Agreement [Member]
Common Stock [Abstract]
Common stock issued (in shares)				12,802
Proceeds from sale of common stock, net				$ 300,000
Common Class A [Member]
Common Stock [Abstract]
Common stock issued (in shares)						289,000
Common Class B [Member]
Common Stock [Abstract]
Number of shares callable by warrants (in shares)						2,711,000

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