Capital Stock - Shares (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CAPITAL STOCK
Preferred Shares, shares authorized	2,000,000	2,000,000	2,000,000
Preferred Shares, shares issued	0	0	0
Preferred Shares, shares outstanding	0	0	0
Common Shares, shares authorized	120,000,000	120,000,000	120,000,000
Common Shares, par value (in dollars per share)	$ 0	$ 0	$ 0
Common Shares, shares outstanding	51,768,424	51,527,711	51,501,877
Share Issuances related to Equity Compensation:
Shares issued upon exercise of stock options by employees	28,384	25,834	657,998
Proceeds realized from stock option exercises (in dollars)	$ 123,603	$ 80,161	$ 2,780,188
Average exercise price of options exercised (in dollars per share)	$ 4.35	$ 3.10	$ 4.23
Restricted Stock Grants (in shares)	530,000		850,000
Share issuances in Exchange for Services
Value of Shares issued in Exchange for Services (in dollars)	$ 228,847