Summary Of Significant Accounting Policies (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013 sqft
Summary Of Significant Accounting Policies [Line Items]
Date of establishment	1948
Square footage of operating properties	50,400,000
Rental Revenues [Member] | Tenant Base [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	3.20%
Net Operating Income [Member] | Houston, Texas Geographic Concentration [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	20.00%
Net Operating Income [Member] | Other Parts of Texas Geographic Concentration [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	7.80%