Segmented Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Geographical Information
Revenues, total	$ 86,390	$ 82,108	$ 271,385	$ 265,437
Greater China [Member]
Geographical Information
Revenues, total	26,557	30,480	85,813	81,967
United States [Member]
Geographical Information
Revenues, total	24,316	20,763	84,553	86,476
Asia (excluding Greater China) [Member]
Geographical Information
Revenues, total	13,534	13,909	32,287	34,510
Western Europe [Member]
Geographical Information
Revenues, total	8,433	6,879	28,809	26,191
Latin America [Member]
Geographical Information
Revenues, total	2,912	2,469	7,725	8,804
Canada [Member]
Geographical Information
Revenues, total	1,993	2,106	6,485	8,116
Russia & the CIS [Member]
Geographical Information
Revenues, total	2,909	3,142	10,216	7,478
Rest of the World [Member]
Geographical Information
Revenues, total	$ 5,736	$ 2,360	$ 15,497	$ 11,895