Description Of Business And Segment Reporting (Reconciliation To Net Income Attributable To Common Shareholders) (Details) $ in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017 NZD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Operating income		$ 20,561	$ 20,311	[1]	$ 23,696	[1]
Depreciation and amortization expense		(16,942)	(15,689)	[1]	(14,562)	[1]
General and administrative expense		(25,347)	(26,906)	[1]	(18,652)	[1]
Interest expense, net		(6,194)	(6,782)	[1]	(7,304)	[1]
Income tax benefit (expense)		(3,337)	(4,020)	[1]	(5,148)	[1]
Equity earnings of unconsolidated joint ventures		815	999	[1]	1,204	[1]
Gain on sale of assets		9,360	393	[1]	11,023	[1]
Casualty gain (loss)	$ 12.7	9,217	(1,421)	[1]
Other income (expense)		588	(63)	[1]	(440)	[1]
Income before income taxes		34,347	13,437	[1]	28,179	[1]
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		40,981	42,427		38,914
Depreciation and amortization expense		(16,469)	(15,294)		(14,268)
Corporate, Non-segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense		(473)	(395)		(294)
General and administrative expense		(19,947)	(21,721)		(14,924)
Interest expense, net		(6,194)	(6,782)		(7,304)
Equity earnings of unconsolidated joint ventures		815	999		1,204
Gain on sale of assets		9,360	393		11,023
Casualty gain (loss)		9,217	(1,421)
Other income (expense)		588	(63)		(440)
Income before income taxes		$ 34,347	$ 13,437		$ 28,179

[1] Certain prior year balances have been reclassified to conform to the 2017 presentation (see Note 2 - Summary of Significant Accounting Policies - Reclassifications).