Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net loss	$ (182,393)	$ (125,373)	$ (78,882)
Items not involving cash:
Depreciation	3,541	1,624	906
Deferred income tax (recovery) expense	(292)	(44)	58
Stock-based compensation	32,372	20,376	10,017
Unrealized foreign exchange (gain) loss	(640)	2,729	327
Unrealized fair value (gain) loss on trading securities	(3,550)	2,934	719
Changes in operating assets and liabilities:
Accounts receivable	130	1,757	(459)
Prepaid expenses and other current assets	1,574	(10,495)	(1,517)
Accounts payable and accrued expenses	3,931	8,062	2,971
Deferred revenue			(3,642)
Net cash used in operating activities	(145,327)	(98,430)	(69,502)
Investing activities:
Purchases of property, plant and equipment	(5,617)	(2,894)	(2,050)
Purchase of marketable securities	(793,907)	(551,137)	(389,474)
Proceeds from marketable securities	682,354	258,028	144,754
Net cash used in investing activities	(117,170)	(296,003)	(246,770)
Financing activities:
Issuance of common shares and pre-funded warrants, net of issuance costs (note 10a and note 10e)	353,487	277,766	447,283
Issuance of common shares pursuant to exercise of stock options	35	705	260
Net cash provided by financing activities	353,522	278,471	447,543
Effect of exchange rate changes on cash and cash equivalents	376	(2,484)	(592)
Increase (decrease) in cash and cash equivalents	91,401	(118,446)	130,679
Cash and cash equivalents, beginning of year	57,242	175,688	45,009
Cash and cash equivalents, end of year	148,643	57,242	175,688
Supplemental disclosures:
Cash paid for operating lease	1,624	919	824
Cash received for lease incentives	1,489
Supplemental disclosures of non-cash transactions:
Fair value of stock options exercised on a cashless basis	5,250	4,491	3,349
Fair value of pre-funded warrants exercised	$ 35,913
Purchases of property, plant and equipment included in accounts payable and accrued expenses		391
Right-of-use asset obtained in exchange for new operating lease liability (note 8)		$ 3,019
Increase in operating lease liability and accounts receivable related to lease incentives claimed in the period (note 8)			493
Increase in operating lease right-of-use asset and operating lease liability related to lease amendments (note 8)			$ 5,248