Share Capital - Stock Option Activity (Details) - shares		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, Beginning balance		2,795,941	2,258,237	2,339,905	1,910,823	1,910,823
Number of Options, Granted		122,750	29,750	686,450	446,500
Number of Options, Exercised	[1]	(34,051)	(3,085)	(118,719)	(71,006)
Number of Options, Forfeited, cancelled or expired		(52,655)	(8,005)	(75,651)	(9,420)
Number of Options Outstanding, Ending balance		2,831,985	2,276,897	2,831,985	2,276,897	2,339,905
Number of Options Exercisable		1,560,573	1,374,535	1,560,573	1,374,535

[1] During the six months ended June 30, 2018, 36,007 stock options were exercised for the same number of common shares for cash (six months ended June 30, 2017 – 63,425). In the same period, the Company issued 34,524 common shares (six months ended June 30, 2017 – 4,405) for the cashless exercise of 82,712 stock options (six months ended June 30, 2017 – 7,581).