Fair Value Of Financial Instruments (Summary Of Carrying Amount And Fair Value Of Financial Instruments) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes and debentures, carrying value	$ 1,076,545,000	$ 1,004,635,000
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	275,000,000
Derivative, Fixed Interest Rate	1.72%
Total Fixed Interest Rate During SWAP	3.17%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	4,200,000
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Interest Expense	4,100,000	300,000
Other Comprehensive Income (Loss), Net of Tax	(8,448,000)	(3,940,000)	0
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, carrying value	1,060,364,000	1,042,682,000
Senior notes and debentures, carrying value	1,076,545,000	1,004,635,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, fair value	1,110,757,000	1,099,273,000
Senior notes and debentures, fair value	1,190,833,000	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
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	12,388,000	3,940,000
Accumulated Other Comprehensive Income (Loss) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Comprehensive Income (Loss), Net of Tax	$ (8,448,000)	$ (3,940,000)