Mortgage and Other Indebtedness, Derivative Instrument Risk (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in Earnings (Effective Portion)	$ (557)	$ (562)
Gain Recognized in Earnings (Ineffective Portion)	0	0
Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	2,181
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in OCI/L (Effective Portion)	$ 276	$ 284