Fair Value Of Financial Instruments (Summary Of Carrying Amount And Fair Value Of Financial Instruments) (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes and debentures, carrying value	$ 1,213,333,000	$ 1,213,333,000	$ 1,076,545,000
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	275,000,000	275,000,000
Derivative, Fixed Interest Rate	1.72%	1.72%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	4,100,000	4,100,000
Other Comprehensive Income (Loss)	8,405,000	10,020,000
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Interest Expense	1,100,000	2,100,000
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, carrying value	1,024,963,000	1,024,963,000	1,060,364,000
Senior notes and debentures, carrying value	1,213,333,000	1,213,333,000	1,076,545,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, fair value	1,064,453,000	1,064,453,000	1,110,757,000
Senior notes and debentures, fair value	1,262,466,000	1,262,466,000	1,190,833,000
Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of Interest Rate Derivatives Held	2	2
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	2,368,000	2,368,000	12,388,000
Accumulated Other Comprehensive Income (Loss) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Comprehensive Income (Loss)		$ 10,020,000