Condensed consolidated statements of cash flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (2,209)	$ (11,705)
Non-cash items:
Stock-based compensation (Note 6(c))	1,866	2,825
Unrealized foreign exchange loss and others	155	322
Changes in operating assets and liabilities:
Receivable, prepayments and deposits	(246)	(174)
Accounts payable and other liabilities	(3,792)	2,324
Cash used in operating activities	(4,226)	(6,408)
Investing activities
Proceeds from maturity of investments		53,000
Purchase of property and equipment		(69)
Cash provided by investing activities		52,931
Financing activities
Proceeds from exercise of stock options		602
Payment on finance lease obligations	(4)	(8)
Cash (used in) provided by financing activities	(4)	594
Effect of exchange rate changes on cash and cash equivalents	2	(19)
Net change in cash and cash equivalents during the period	(4,228)	47,098
Cash and cash equivalents, beginning of period	76,928	52,032
Cash and cash equivalents, end of period	72,700	99,130
Supplemental disclosure of cash flow information:
Interest received	$ 880	$ 736