Operations In Foreign Currency (Summary Of Currency Exchange Rates) (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Australian Dollar [Member] | Spot Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7104	0.7690	0.7046
Australian Dollar [Member] | Average Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7123	0.7861	0.7479
New Zealand Dollar [Member] | Spot Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.6820	0.7239	0.6711
New Zealand Dollar [Member] | Average Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.6816	0.7275	0.6930