Stock Option Plan - Stock Option Activity (Details) - shares		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, beginning of period		1,785,436	1,445,320	1,484,218	1,333,099	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	1,484,218
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.