Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2011
Summary Of Significant Accounting Policies (Textual) [Abstract]
Average lease term period	6 years
Percentage of taxable income distribute	100.00%
Consolidation percentage if not wholly owned but controlled	less than 100%
Depreciation commencement description	Depreciation commences at the earlier of stabilization (defined as 90% occupied) or one year after completion of construction.
Percentage of occupancy for stabilization	90.00%
Period after completion of construction for commencement of depreciation	1 year
Investment maturity period	Three months or less
Capital improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives Minimum	5
Estimated useful Lives Maximum	7
Tenant Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives	10
Depreciable and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives	25
Industrial Properties Acquired [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives	30
Office and Retail Properties [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives	40
Leasehold development [Member]
Property, Plant and Equipment [Line Items]
Estimated useful Lives	40