Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Total	$ 2,323,620	[1]	$ 2,204,030	[1]
As To Interest Rate [Member]
Debt Instrument [Line Items]
Fixed-rate debt	2,179,715		1,992,599
Variable-rate debt	143,905		211,431
Total	2,323,620		2,204,030
As To Collateralization [Member]
Debt Instrument [Line Items]
Unsecured debt	1,438,838		1,270,742
Secured debt	884,782		933,288
Total	$ 2,323,620		$ 2,204,030

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