Stock Option Plan - Stock Option Activity (Details) - shares		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, beginning of period		1,745,018	1,442,741	1,484,218	1,333,099	1,333,099
Granted		4,100	6,273	384,538	163,504
Exercised	[1]	(110,039)	(1,028)	(209,850)	(1,800)
Forfeited and expired		(1,905)	(4,411)	(21,732)	(51,228)
Outstanding, end of period		1,637,174	1,443,575	1,637,174	1,443,575	1,484,218
Exercisable, end of period		1,052,955	1,078,009	1,052,955	1,078,009

[1] During the nine months ended September 30, 2015, 62,469 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 100,465 common shares for the cashless exercise of 147,381 stock options.