Fair Value Of Financial Instruments (Summary Of Carrying Amount And Fair Value Of Financial Instruments) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loss on Derivative Instruments, Pretax	$ 1,100,000		$ 3,100,000
Senior notes and debentures, carrying value	1,076,456,000		1,076,456,000		1,004,635,000
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	275,000,000		275,000,000
Derivative, Fixed Interest Rate	1.72%		1.72%
TotalFixedInterestRateDuringSWAP	3.17%		3.17%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	4,200,000		4,200,000
Other Comprehensive Income (Loss)	(2,852,000)	0	(9,287,000)	0
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, carrying value	1,030,261,000		1,030,261,000		1,042,682,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, fair value	1,071,901,000		1,071,901,000		1,099,273,000
Senior notes and debentures, fair value	1,204,598,000		1,204,598,000		1,085,309,000
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	13,227,000		13,227,000		3,940,000
Accumulated Other Comprehensive Income (Loss) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Comprehensive Income (Loss)			$ (9,287,000)