Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Schedule of Long-term Debt, By Type [Line Items]
Secured debt	$ 66,000
Total	1,940,897	[1]	1,938,188	[1]
As To Interest Rate [Member]
Schedule of Long-term Debt, By Type [Line Items]
Fixed-rate debt	1,740,075		1,651,959
Variable-rate debt	200,822		286,229
Total	1,940,897		1,938,188
As To Collateralization [Member]
Schedule of Long-term Debt, By Type [Line Items]
Unsecured debt	1,368,350		1,343,217
Secured debt	572,547		594,971
Total	$ 1,940,897		$ 1,938,188

[1] Consolidated variable interest entities' assets held as collateral and debt included in the above balances (see Note 15):