Fair Value Of Financial Instruments (Summary Of Carrying Amount And Fair Value Of Financial Instruments) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Interest Expense	$ 1,000,000
Senior notes and debentures, carrying value	1,076,635,000	1,076,545,000
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	275,000,000
Derivative, Fixed Interest Rate	1.72%
TotalFixedInterestRateDuringSWAP	3.17%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	4,100,000
Other Comprehensive Income (Loss)	1,615,000
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, carrying value	1,047,573,000	1,060,364,000
Senior notes and debentures, carrying value	1,076,635,000	1,076,545,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, fair value	1,093,060,000	1,110,757,000
Senior notes and debentures, fair value	1,190,833,000	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
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	10,773,000	12,388,000
Accumulated Other Comprehensive Income (Loss) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Comprehensive Income (Loss)	$ 1,615,000