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
Jun. 30, 2017
Dec. 31, 2016
Real Estate Properties [Line Items]    
Properties under development or held for future development $ 46,154 $ 40,232
Real estate investment property, at cost 2,818,290 $ 2,685,403
Army Navy Building [Domain]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 4,100  
Real estate investment property, at cost 3,400  
The Wellington land parcel [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 23,800  
Riverside Developments [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development 18,300  
Spring Vally Retail Center [Member]    
Real Estate Properties [Line Items]    
Properties under development or held for future development $ 1,600