Real Estate (Summary Of Real Estate Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Cost	$ 7,635,061	$ 6,759,073
Accumulated Depreciation and Amortization	(1,876,544)	(1,729,234)
Encumbrances	563,061	542,707
Retail and mixed-use properties
Real Estate Properties [Line Items]
Cost	7,500,929	6,621,170
Accumulated Depreciation and Amortization	(1,821,046)	(1,677,938)
Encumbrances	470,720	449,896
Retail properties under capital leases
Real Estate Properties [Line Items]
Cost	123,346	127,359
Accumulated Depreciation and Amortization	(46,140)	(42,308)
Encumbrances	71,556	71,590
Residential
Real Estate Properties [Line Items]
Cost	10,786	10,544
Accumulated Depreciation and Amortization	(9,358)	(8,988)
Encumbrances	$ 20,785	$ 21,221