Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Total	$ 2,227,419	[1]	$ 2,531,837	[1]
As To Interest Rate [Member]
Debt Instrument [Line Items]
Fixed-rate debt	1,831,791		2,014,834
Variable-rate debt	395,628		517,003
Total	2,227,419		2,531,837
As To Collateralization [Member]
Debt Instrument [Line Items]
Unsecured debt	1,254,804		1,510,932
Secured debt	972,615		1,020,905
Total	$ 2,227,419		$ 2,531,837

[1] * Consolidated Variable Interest Entities’ Assets and Liabilities included in the above balances (See Note 17):