Stock Option Plan - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, beginning of period	1,484,218		1,333,099
Granted	346,964		157,231
Exercised	(44,656)	[1]	(772)	[1]
Forfeited and expired	(1,090)		(44,238)
Outstanding, end of period	1,785,436		1,445,320
Exercisable, end of period	1,146,383		999,089

[1] During the three months ended March 31, 2015, 26,910 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 14,032 common shares for the cashless exercise of 17,746 stock options.