Stock Option Plan

6 Months Ended

Jun. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock option plan

8. Stock option plan:

The following table presents stock option activity for the period:

	Three Months Ended June 30,						Six Months Ended     June 30,
	2015			2014			2015			2014
Outstanding, beginning of period		1,785,436			1,445,320			1,484,218			1,333,099
Granted		33,474			—			380,438			157,231
Exercised(1)		(55,155	)		—			(99,811	)		(772	)
Forfeited and expired		(18,737	)		(2,579	)		(19,827	)		(46,817	)
Outstanding, end of period		1,745,018			1,442,741			1,745,018			1,442,741
Exercisable, end of period		1,126,629			1,034,518			1,126,629			1,034,518

(1) During the six months ended June 30, 2015, 53,442 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 32,399 common shares for the cashless exercise of 46,369 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 June 30,						Six Months Ended   June 30,
	2015			2014			2015			2014
Average risk-free interest rate		1.71	%		1.97	%		1.71	%		1.97	%
Average expected term (in years)		6.04			6.20			6.23			6.20
Expected volatility		75	%		74	%		75	%		74	%
Expected dividend yield		0.00	%		0.00	%		0.00	%		0.00	%
Expected forfeiture rate		0.00	%		0.00	%		0.00	%		0.00	%

The weighted-average fair value of options granted during the six months ended June 30, 2015 was $11.96 (six months ended June 30, 2014 - $6.57) per option.