Net Income (Loss) Per Common and Preferred Share - Computation of Basic and Diluted Net Loss Per Common and Preferred Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Allocation of loss attributed to shareholders
Basic	$ (6,498)	$ (7,380)	$ (10,560)	$ (14,897)
Basic	$ (1,303)		$ (996)
Weighted average number of shares:
Basic	14,306,491	17,997,194	16,055,456	17,971,702
Diluted	14,306,491	18,015,748	16,055,456	17,995,109
Net loss attributable to shareholders per share - basic	$ (0.45)	$ (0.41)	$ (0.66)	$ (0.83)
Net loss attributable to shareholders per share - diluted	$ (0.45)	$ (0.41)	$ (0.66)	$ (0.84)
Common Shares [Member]
Allocation of loss attributed to shareholders
Basic	$ (6,498)	$ (7,380)	$ (10,560)	$ (14,897)
Adjustment for change in fair value of liability classified stock options		(30)		(162)
Diluted	$ (6,498)	$ (7,410)	$ (10,560)	$ (15,059)
Weighted average number of shares:
Basic	14,306,491	17,997,194	16,055,456	17,971,702
Adjustment for dilutive effect of stock options		18,554		23,407
Diluted	14,306,491	18,015,748	16,055,456	17,995,109
Net loss attributable to shareholders per share - basic	$ (0.45)	$ (0.41)	$ (0.66)	$ (0.83)
Net loss attributable to shareholders per share - diluted	$ (0.45)	$ (0.41)	$ (0.66)	$ (0.84)
Preferred Shares [Member]
Allocation of loss attributed to shareholders
Basic	$ (1,303)		$ (996)
Diluted	$ (1,303)		$ (996)
Weighted average number of shares:
Basic	2,868,000		1,513,667
Diluted	2,868,000		1,513,667
Net loss attributable to shareholders per share - basic	$ (0.45)		$ (0.66)
Net loss attributable to shareholders per share - diluted	$ (0.45)		$ (0.66)