Significant Accounting Policies (Exchange Rates) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Canadian Dollar (CAD) [Member]
Currency [Line Items]
Ending rates	1.2545	1.3427
Average Rates	1.2981	1.3256	1.2786
Average Rates % Change	2.10%	(3.70%)
Euros (EUR) [Member]
Currency [Line Items]
Ending rates	0.8334	0.9476
Average Rates	0.8871	0.9041	0.9014
Average Rates % Change	1.90%	(0.30%)
Polish Zloty (PLN) [Member]
Currency [Line Items]
Ending rates	3.4841	4.2065
Average Rates	3.7764	3.9455	3.7706
Average Rates % Change	4.30%	(4.60%)
British Pound (GBP) [Member]
Currency [Line Items]
Ending rates	0.7396	0.8106
Average Rates	0.7767	0.7410	0.6545
Average Rates % Change	(4.80%)	(13.20%)