Earnings (Loss) per 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
Basic and diluted loss per share
Net loss for the period	$ (17,788)	$ (14,602)	$ (31,130)	$ (29,825)
Weighted average number of shares outstanding	40,515,920	27,186,560	38,723,718	27,197,070
Basic and diluted loss per share	$ (0.44)	$ (0.54)	$ (0.80)	$ (1.10)
Options
Anti-dilutive stock options
Common stock equivalents excluded from the calculations of diluted earnings per share	4,896,520	2,930,110	4,896,520	2,930,110
Restricted Stock Units
Anti-dilutive stock options
Common stock equivalents excluded from the calculations of diluted earnings per share	328,300		328,300