Fair Value Measurement of Financial Instruments (Details) (USD $) In Thousands	Sep. 30, 2011		Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements			$ 691
Interest Rate Swap [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements			691
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements			691
Interest Rate Cap [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	3
Interest Rate Cap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	3
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	16,128	[1]	56,718	[1]
Tenant receivables, net	142,884	[1],[2]	134,006	[1],[2]
Accounts Payable	13,521	[1]	15,763	[1]
Line of credit and notes payable	1,664,525	[2]	1,402,525	[2]
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	16,128	[1]	56,718	[1]
Tenant receivables, net	142,884	[1],[2]	134,006	[1],[2]
Accounts Payable	13,521	[1]	15,763	[1]
Line of credit and notes payable	$ 1,722,246	[2]	$ 1,428,255	[2]

[1] For the periods presented, the carrying value approximates estimated fair value.

[2] For the periods presented, the carrying value and estimated fair value includes assets and liabilities held for sale.