Summary Of Significant Accounting Policies (Narrative) (Details) ft² in Millions	9 Months Ended
	Sep. 30, 2015 ft²
Significant Accounting Policies [Line Items]
Date of establishment	1948
Square footage of operating properties	45.9
Base Minimum Rental Revenue [Member] | Tenant Base [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	3.30%
Net Operating Income [Member] | Houston, Texas Geographic Concentration [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	18.20%
Net Operating Income [Member] | Other Parts of Texas Geographic Concentration [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	10.10%