OTHER INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OTHER INCOME
Unrealized and realized gain (loss) on investments (note 5)	$ 5,259	$ (3,324)	$ 257
Foreign currency gain	1,697	3,922	694
Other income	184	570	270
Total other income	$ 7,140	$ 1,168	$ 1,221