Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 31, 2015	$ 243	$ 244,033	$ (146,307)	$ (5,277)	$ 92,692
Exercise of share options		76			76
Share-based compensation expense		5,019			5,019
Other comprehensive loss				(2,474)	(2,474)
Net loss			(22,349)		(22,349)
Balance at Dec. 31, 2016	243	249,128	(168,656)	(7,751)	72,964
Exercise of share options	4	557			561
Share-based compensation expense		5,864			5,864
Other comprehensive loss				2,039	2,039
Net loss			(32,885)		(32,885)
Issuance of shares in secondary offering	22	39,276			39,298
Tax on vesting of restricted share units		(212)			(212)
Balance at Dec. 31, 2017	269	294,613	(201,541)	(5,712)	87,629
Exercise of share options	7	3,234			3,241
Share-based compensation expense		5,551			5,551
Other comprehensive loss				(2,811)	(2,811)
Net loss			120,779		120,779
Tax on vesting of restricted share units		(383)			(383)
Balance at Dec. 31, 2018	$ 276	$ 303,015	$ (80,762)	$ (8,523)	$ 214,006