Variable Interest Entities VIE Considerations (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 limited	Mar. 31, 2010 installments
Available-for-Sale Securities, Ownership Percentage	100.00%
Number of Variable Interest Entities	5
Unconsolidated Properties [Member]
Number of Variable Interest Entities	2
Total Owners [Member]
Number of Owners	4
Related party owner [Member]
Number of Owners	2
Ashley Square [Member]
Available-for-Sale Securities, Ownership Percentage	100.00%
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	99.00%
Cross Creek [Member]
Available-for-Sale Securities, Ownership Percentage	100.00%
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	99.00%
Number of Partners	3
Partners' Capital Account, Contributions		$ 2,200,000
Number of Installments of Contributed Capital		3
Noncontrolling Interest, Ownership Percentage by Parent	1.00%
First Installment [Member] | Cross Creek [Member]
Partners' Capital Account, Contributions		$ 563,000