Condensed consolidated statements of stockholders' equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2017	$ 98,887		$ 297,459	$ (198,502)	$ (70)
Beginning balance, shares at Dec. 31, 2017		23,472,430
Options exercised	602		602
Options exercised, shares		64,938
Stock-based compensation (Note 6(c))	2,825		2,825
Other comprehensive income	68				68
Net (loss) income	(11,705)			(11,705)
Ending balance at Jun. 30, 2018	90,677		300,886	(210,207)	(2)
Ending balance, shares at Jun. 30, 2018		23,537,368
Beginning balance at Mar. 31, 2018	85,825		298,974	(213,125)	(24)
Beginning balance, shares at Mar. 31, 2018		23,492,161
Options exercised	399		399
Options exercised, shares		45,207
Stock-based compensation (Note 6(c))	1,513		1,513
Other comprehensive income	22				22
Net (loss) income	2,918			2,918
Ending balance at Jun. 30, 2018	90,677		300,886	(210,207)	$ (2)
Ending balance, shares at Jun. 30, 2018		23,537,368
Beginning balance at Dec. 31, 2018	$ 72,672		302,759	(230,087)
Beginning balance, shares at Dec. 31, 2018	23,537,368	23,537,368
Options exercised, shares	0
Stock-based compensation (Note 6(c))	$ 1,866		1,866
Net (loss) income	(2,209)			(2,209)
Ending balance at Jun. 30, 2019	$ 72,329		304,625	(232,296)
Ending balance, shares at Jun. 30, 2019	23,537,368	23,537,368
Beginning balance at Mar. 31, 2019	$ 71,542		303,837	(232,295)
Beginning balance, shares at Mar. 31, 2019		23,537,368
Options exercised, shares	0
Stock-based compensation (Note 6(c))	$ 788		788
Net (loss) income	(1)			(1)
Ending balance at Jun. 30, 2019	$ 72,329		$ 304,625	$ (232,296)
Ending balance, shares at Jun. 30, 2019	23,537,368	23,537,368