Share Capital (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Activity

The following table presents stock option activity for the period:

	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Outstanding, beginning of period		2,795,941			2,258,237			2,339,905			1,910,823
Granted		122,750			29,750			686,450			446,500
Exercised(1)		(34,051	)		(3,085	)		(118,719	)		(71,006	)
Forfeited, cancelled or expired		(52,655	)		(8,005	)		(75,651	)		(9,420	)
Outstanding, end of period		2,831,985			2,276,897			2,831,985			2,276,897
Exercisable, end of period		1,560,573			1,374,535			1,560,573			1,374,535

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).

Fair Value Assumptions for Stock Options

The fair value of each stock option granted is estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Average risk-free interest rate		2.88	%		2.05	%		2.79	%		2.41	%
Expected volatility		75	%		81	%		75	%		81	%
Average expected term (in years)		7.65			7.68			7.41			7.49
Expected dividend yield		0	%		0	%		0	%		0	%
Weighted average fair value of stock optionsgranted	$	4.54		$	2.92		$	3.61		$	6.11