Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Operating activities:
Net loss		$ (7,659)	$ (21,348)
Items not involving cash:
Depreciation		271	179
Amortization of discount on term loan		216	255
Deferred income tax recovery		(52)	(11)
Stock-based compensation		2,487	955
Unrealized foreign exchange (gain) loss		23	(225)
Unrealized gain on marketable securities		(532)	(143)
Loss on repayment of term loan (note 9)	$ 988	988
Changes in operating assets and liabilities:
Accounts receivable		(1,009)	(15)
Prepaid expenses and other current assets		225	522
Accounts payable and accrued expenses		(1,054)	2,388
Deferred revenue		(17,760)
Net cash used in operating activities		(23,856)	(17,443)
Investing activities:
Purchases of property, plant and equipment		(1,016)	(600)
Purchases of marketable securities		(146,773)	(64,176)
Proceeds from marketable securities		105,798	51,145
Net cash used in investing activities		(41,991)	(13,631)
Financing activities:
Repayment of term loan and repayment fees (note 9)		(16,743)
Issuance of common shares, net of issuance costs (note 10a)		102,456
Issuance of common shares pursuant to exercise of stock options		37	69
Net cash provided by financing activities		85,750	69
Effect of exchange rate changes on cash and cash equivalents		(459)	326
Increase (decrease) in cash and cash equivalents		19,444	(30,679)
Cash and cash equivalents, beginning of period		24,755	67,754	$ 67,754
Cash and cash equivalents, end of period	$ 44,199	44,199	37,075	$ 24,755
Supplemental disclosures:
Interest paid		339	468
Interest received		2,191	1,269
Cash paid for operating lease		311	314
Supplemental disclosures of non-cash transactions:
Fair value of stock options exercised on a cashless basis		$ 876	$ 9