Quarterly report pursuant to Section 13 or 15(d)

Real Estate - Development/Redevelopment (Details)

v3.7.0.1
Real Estate - Development/Redevelopment (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Real Estate Properties [Line Items]    
Properties under development or held for future development $ 42,914 $ 40,232
Real Estate Investment Property, at Cost 2,697,122 $ 2,685,403
Army Navy Building [Domain]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 3,400  
Real Estate Investment Property, at Cost 1,000  
The Wellington land parcel [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 20,700  
Riverside Developments [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 17,100  
Spring Vally Retail Center [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development $ 1,100