Summary of Significant Accounting Policies: (Details 2)	12 Months Ended
	Dec. 31, 2012
Investment in unconsolidated joint ventures
Threshold ownership percentage above which to use equity method of accounting only if no controlling financial interest	50.00%
Buildings and improvements | Minimum
Property, Plant and Equipment
Estimated useful lives of assets	5 years
Buildings and improvements | Maximum
Property, Plant and Equipment
Estimated useful lives of assets	40 years
Tenant improvements | Minimum
Property, Plant and Equipment
Estimated useful lives of assets	5 years
Tenant improvements | Maximum
Property, Plant and Equipment
Estimated useful lives of assets	7 years
Equipment and furnishings | Minimum
Property, Plant and Equipment
Estimated useful lives of assets	5 years
Equipment and furnishings | Maximum
Property, Plant and Equipment
Estimated useful lives of assets	7 years