Summary Of Significant Accounting Policies (Narrative) (Details)	6 Months Ended
	Jun. 30, 2013 sqft
Summary Of Significant Accounting Policies [Line Items]
Date of establishment	1948
Square footage of operating properties	51,500,000
Tenant Base [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	3.20%
Houston, Texas Geographic Concentration [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	20.40%
Other Parts of Texas Geographic Concentration [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentrations of risk	7.50%