Nature of Business and Significant Accounting Policies, Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Potential shares of common stock that are not included in the calculation of diluted net loss per share [Abstract]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)	1,663,061	263,290
Reconciliation of reported net loss with reported net loss per share [Abstract]
Net loss	$ (15,836)	$ (18,114)
Deemed dividend to preferred shareholders (see Note 5)	(1,757)	(4,509)
Net loss after deemed dividend	$ (17,593)	$ (22,623)
Weighted average shares outstanding (in shares)	1,649,000	81,000
Basic and diluted loss per share (in dollars per share)	$ (10.67)	$ (278.90)
March 2020 Offering [Member]
Loss per share [Abstract]
Net deemed dividends resulting from subsequent reduction in exercise price of warrants	$ 200
Stock Options [Member]
Potential shares of common stock that are not included in the calculation of diluted net loss per share [Abstract]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)	16,889	13,471
Warrants to Purchase Common Stock [Member]
Potential shares of common stock that are not included in the calculation of diluted net loss per share [Abstract]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)	1,631,948	231,629
Series F Convertible Preferred Stock [Member]
Potential shares of common stock that are not included in the calculation of diluted net loss per share [Abstract]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)	14,224	18,190