Stock Option Plan (Tables)

3 Months Ended

Mar. 31, 2016

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,
	2016			2015
Outstanding, beginning of period		1,721,472			1,484,218
Granted		233,950			346,964
Exercised(1)		(16,246	)		(44,656	)
Forfeited and expired		(4,442	)		(1,090	)
Outstanding, end of period		1,934,734			1,785,436
Exercisable, end of period		1,151,853			1,146,383

⁽¹⁾ During the three months ended March 31, 2016, 16,246 stock options were exercised for the same number of common shares for cash (three months ended March 31, 2015 – 26,910). In the same period, the Company did not issue any common shares (three months ended March 31, 2015 – 14,032) for the cashless exercise of stock options (three months ended March 31, 2015 – 17,746).

Fair Value Assumptions for Stock Options

The fair value of each option issued to employees and non-employees is estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Three Months Ended March 31,
	2016			2015
Average risk-free interest rate		1.64	%		1.71	%
Average expected term (in years)		6.25			6.25
Expected volatility		75	%		75	%
Expected dividend yield		0.00	%		0.00	%