Mortgage and Other Indebtedness Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Derivatives	$ 125,000
Pay Fixed Receive Variable Swap One [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Derivatives	56,444
Amortized amount	48,337
Pay fixed receive variable swap Two [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Derivatives	35,333
Amortized amount	30,276
Pay fixed receive variable swap Three [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Derivatives	13,212
Amortized amount	11,313
Pay fixed receive variable swap Four [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Derivatives	11,759
Amortized amount	10,083
Interest Rate Cap [Member]
Derivatives, Fair Value [Line Items]
Derivative, Number of Instruments Held	1
Notional Amount of Interest Rate Derivatives	125,000
Amortized amount	122,375
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative, Number of Instruments Held	4
Notional Amount of Interest Rate Derivatives	116,748	117,700
Cash Flow Hedging [Member] | Pay Fixed Receive Variable Swap One [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Description of Variable Rate Basis	1-month LIBOR
Derivative, Basis Spread on Variable Rate	2.149%
Interest Rate Derivatives, at Fair Value, Net	(2,532)	(2,674)
Derivative, Maturity Date	Apr. 30, 2016
Cash Flow Hedging [Member] | Pay fixed receive variable swap Two [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Description of Variable Rate Basis	1-month LIBOR
Derivative, Basis Spread on Variable Rate	2.187%
Interest Rate Derivatives, at Fair Value, Net	(1,632)	(1,725)
Derivative, Maturity Date	Apr. 30, 2016
Cash Flow Hedging [Member] | Pay fixed receive variable swap Three [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Description of Variable Rate Basis	1-month LIBOR
Derivative, Basis Spread on Variable Rate	2.142%
Interest Rate Derivatives, at Fair Value, Net	(589)	(622)
Derivative, Maturity Date	Apr. 30, 2016
Cash Flow Hedging [Member] | Pay fixed receive variable swap Four [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Description of Variable Rate Basis	1-month LIBOR
Derivative, Basis Spread on Variable Rate	2.236%
Interest Rate Derivatives, at Fair Value, Net	(563)	(596)
Derivative, Maturity Date	Apr. 30, 2016
Cash Flow Hedging [Member] | Interest Rate Cap [Member] | Intangible lease assets and other assets [Member]
Derivatives, Fair Value [Line Items]
Derivative, Description of Variable Rate Basis	3-month LIBOR
Derivative, Basis Spread on Variable Rate	5.00%
Interest Rate Derivatives, at Fair Value, Net	$ 3	$ 0
Derivative, Maturity Date	Jan. 01, 2014