Operation in Foreign Currency (Summary Of Currency Exchange Rates) (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2017 USD ($)	Mar. 31, 2016	Dec. 31, 2016
Currency Exchange Rates [Line Items]
Gain recognized on foreign currency transactions	$ 825
Australian Dollar [Member] \| Spot Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7638	0.7677	0.7230
Australian Dollar [Member] \| Average Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7584	0.7216	0.7440
New Zealand Dollar [Member] \| Spot Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7001	0.6926	0.6958
New Zealand Dollar [Member] \| Average Rate [Member]
Currency Exchange Rates [Line Items]
Foreign currency exchange rate	0.7122	0.6637	0.6973

Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30690-110894

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30700-110894

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration