Net Loss Per Common Share (Computation of Basic and Diluted Net Loss Per Share) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Abstract]
Net loss	$ (12,838,000)	$ (18,838,000)
Excess of fair value of consideration transferred on conversion of Series B Preferred Stock		(3,580,000)
Accretion of Series B redeemable convertible preferred stock		(1,858,000)
Net loss attributable to common stockholders - basic	(12,838,000)	(24,276,000)
Change in fair value of November 2016 warrants	(1,524,000)
Net loss attributable to common stockholders - diluted	$ (14,362,000)	$ (24,276,000)
Weighted average number of shares of common stock outstanding - basic	6,387,425	983,846
Net loss per share of common stock - basic	$ (2.01)	$ (24.67)
Weighted average number of shares of common stock outstanding - diluted	6,574,117	983,846
Net loss per share of common stock - diluted	$ (2.18)	$ (24.67)