Share Capital - Stock Option Activity (Details) - shares		3 Months Ended				6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, Beginning balance		4,527,992	3,534,236	2,667,449	2,671,906	3,534,236	2,671,906
Number of Options, Granted		127,300		0		1,245,650	21,900
Number of Options, Exercised	[1]	(54,716)		(3,461)		(153,042)	(25,863)
Number of Options, Forfeited, cancelled or expired		(5,144)		(200)		(31,412)	(4,155)
Number of Options Outstanding, Ending balance		4,595,432	4,527,992	2,663,788	2,667,449	4,595,432	2,663,788
Number of Options Exercisable, End of period		2,114,647		1,913,129		2,114,647	1,913,129

[1] During the six months ended June 30, 2020, 10,715 stock options were exercised for the same number of common shares for cash (six months ended June 30, 2019 – 23,472). In the same period, the Company issued 85,660 common shares (six months ended June 30, 2019 – 863) for the cashless exercise of 142,327 stock options (six months ended June 30, 2019 – 2,391).