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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allocation of loss attributed to shareholders
Basic	$ (12,762)	$ (7,742)	$ (23,433)	$ (22,639)
Basic	$ (1,621)		$ (2,506)
Weighted average number of shares:
Basic	20,306,298	17,998,420	17,472,403	17,980,608
Diluted	20,306,298	18,009,979	17,472,403	18,000,066
Net loss attributable to shareholders per share - basic	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.26)
Net loss attributable to shareholders per share - diluted	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.27)
Common Shares [Member]
Allocation of loss attributed to shareholders
Basic	$ (12,762)	$ (7,742)	$ (23,433)	$ (22,639)
Adjustment for change in fair value of liability classified stock options		(20)		(182)
Diluted	$ (12,762)	$ (7,762)	$ (23,433)	$ (22,821)
Weighted average number of shares:
Basic	20,306,298	17,998,420	17,472,403	17,980,608
Adjustment for dilutive effect of stock options		11,559		19,458
Diluted	20,306,298	18,009,979	17,472,403	18,000,066
Net loss attributable to shareholders per share - basic	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.26)
Net loss attributable to shareholders per share - diluted	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.27)
Preferred Shares [Member]
Allocation of loss attributed to shareholders
Basic	$ (1,621)		$ (2,506)
Diluted	$ (1,621)		$ (2,506)
Weighted average number of shares:
Basic	2,579,111		1,868,815
Diluted	2,579,111		1,868,815
Net loss attributable to shareholders per share - basic	$ (0.63)		$ (1.34)
Net loss attributable to shareholders per share - diluted	$ (0.63)		$ (1.34)