Real Estate Transactions (Details) (USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2013
Property
Jun. 30, 2012
Jun. 30, 2013
Property
Jun. 30, 2012
Business Combinations [Abstract]        
Number of properties sold 5   5  
Sale of productive assets, sale price     $ 14,600,000  
Proceeds from sale of real estate assets and property condemnation     14,019,000 75,000
Gain on sale of unconsolidated joint venture interests     305,000  
Impairment of real estate assets 0 1,979,000 1,152,000 1,979,000
Disposal group, including discontinued operation, revenue     388,000 764,000
Disposal group, including discontinued operation, net income excluding gain on sale     $ 228,000 $ 179,000