Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Information [Line Items]
Loss from operations	$ (3,258)	$ (4,320)	$ (5,003)	$ (4,990)	$ (5,783)		$ (5,842)	$ (6,475)	$ (8,149)
Net (loss) income	$ (3,193)	$ (3,689)	$ (4,214)	$ (2,326)	$ 2,812		$ (10,930)	$ (4,315)	$ (3,058)	$ (13,367)	$ (15,174)
Net (loss) income per share - basic	$ (1.12)	$ (0.93)	$ (1.05)	$ (0.70)	$ 0.76		$ (4.90)	$ (1.05)	$ (0.70)
Net (loss) income per share - dilutive	$ (1.12)	$ (0.93)	$ (1.05)	$ (0.70)	$ 0.76		$ (4.90)	$ (1.05)	$ (0.70)
Weighted average common share - basic	13,442,104	4,028,304	3,683,384	3,673,340	3,673,340		3,665,134	3,514,435	3,355,636
Weighted average common share - dilutive	13,442,104	4,028,304	3,683,384	3,673,340	3,673,340		3,665,134	3,514,435	3,355,636

[1] Net Income due to gain on remeasurement of the warrant liabilities in excess of the quarter to date loss.