Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

The common share activity for 2021, 2020 and 2019 is as follows:


	Common Shares
	Number of shares (in thousands)	Amount (in thousands)
Balance at December 31, 2018	85,500	$	488,744
Issued pursuant to Public Offering	12,782	191,737
Issued pursuant to At-the-Market (ATM) Facilities	6,953	45,010
Share issue costs	—	(13,629)
Issued pursuant to exercise of warrants	2,983	12,428
Issued pursuant to exercise of stock options	3,580	22,197
Balance at December 31, 2019	111,798	746,487
Issued pursuant to Public Offering	13,333	200,000
Share issue costs	—	(12,268)
Issued pursuant to exercise of warrants	1	2
Issued pursuant to exercise of stock options	1,593	10,107
Balance at December 31, 2020	126,725	944,328
Issued pursuant to ATM Facilities	10,166	202,356
Share issue costs	—	(5,616)
Issued pursuant to exercise of warrants	1,434	2,102
Issued pursuant to exercise of stock options	3,238	33,073
Issued pursuant to ESPP	37	808
Balance at December 31, 2021	141,600	$	1,177,051

The warrant activity for 2021 and 2020 is as follows:


			Number of warrants (in thousands)
Balance at December 31, 2019			1,691
Warrants exercised			(1)
Balance at December 31, 2020			1,690
Warrants exercised			(1,684)
Warrants expired			(6)
Balance at December 31, 2021			—