Mortgage and Other Indebtedness, Derivative Instrument Risk (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in Earnings (Effective Portion)	$ (562)	$ (22)
Gain Recognized in Earnings (Ineffective Portion)	0	0
Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification of losses currently reported in accumulated other comprehensive income to interest expense in the next twelve months	1,905
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Recognized in OCI/L (Effective Portion)	$ 284	$ 562