Nature of Business and Significant Accounting Policies, Income Taxes and Loss Per Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
U.S. corporate income tax rate		34.00%
Percentage of valuation allowance on deferred tax assets		100.00%
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		9,402,231	102,300
Reported net loss with reported net loss per share [Abstract]
Net loss		$ (13,382,000)	$ (15,792,000)
Deemed dividend to preferred shareholders (see Note 6)		(11,590,000)	(1,900,000)
Net loss after deemed dividend		$ (24,972,000)	$ (17,692,000)
Weighted average shares outstanding (in shares)		665,000	33,000
Basic and diluted loss per share (in dollars per share)		$ (37.51)	$ (536.12)
Series E Convertible Preferred Stock [Member]
Reported net loss with reported net loss per share [Abstract]
Deemed dividend to preferred shareholders (see Note 6)		$ (1,000,000)
Series F Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		842,940	0
Reported net loss with reported net loss per share [Abstract]
Deemed dividend to preferred shareholders (see Note 6)		$ (8,700,000)
Series C and D Convertible Preferred Stock [Member]
Reported net loss with reported net loss per share [Abstract]
Deemed dividend to preferred shareholders (see Note 6)		(1,800,000)
Series B and B-1 Convertible Preferred Stock [Member]
Reported net loss with reported net loss per share [Abstract]
Deemed dividend to preferred shareholders (see Note 6)		$ (1,900,000)	$ (1,900,000)
Series B, C And D Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		0	53,179
Plan [Member]
Income Tax Disclosure [Line Items]
U.S. corporate income tax rate	21.00%
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		36,362	4,354
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		245	499
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that are not included in the calculation of diluted net loss per share (in shares)		8,522,684	44,268