Share Capital (Tables)

3 Months Ended

Mar. 31, 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 March 31,
	2018			2017
Outstanding, beginning of period		2,339,905			1,910,823
Granted		563,700			416,750
Exercised(1)		(84,668	)		(67,921	)
Forfeited, cancelled or expired		(22,996	)		(1,415	)
Outstanding, end of period		2,795,941			2,258,237
Exercisable, end of period		1,505,459			1,293,367

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).

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 March 31,
	2018			2017
Average risk-free interest rate		2.77	%		2.44	%
Expected volatility		75	%		81	%
Average expected term (in years)		7.36			7.47
Expected dividend yield		0	%		0	%
Weighted average fair value of stock options granted	$	3.41		$	6.34