Share Capital - Stock Option Activity (Details) - shares		3 Months Ended		12 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, Beginning balance		2,339,905	1,910,823	1,910,823
Number of Options, Granted		563,700	416,750
Number of Options, Exercised	[1]	(84,668)	(67,921)
Number of Options, Forfeited, cancelled or expired		(22,996)	(1,415)
Number of Options Outstanding, Ending balance		2,795,941	2,258,237	2,339,905
Number of Options Exercisable		1,505,459	1,293,367

[1] During the three months ended March 31, 2018, 13,374 stock options were exercised for the same number of common shares for cash (three months ended March 31, 2017 – 62,397). In the same period, the Company issued 27,507 common shares (three months ended March 31, 2017 – 3,693) for the cashless exercise of 71,294 stock options (three months ended March 31, 2017 – 5,524).