Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Acquisitions) (Narrative) (Details)

v3.6.0.2
Recent Transactions (Acquisitions) (Narrative) (Details)
$ in Thousands
12 Months Ended
Feb. 27, 2017
USD ($)
item
Feb. 02, 2017
USD ($)
ft²
property
Jan. 11, 2017
USD ($)
ft²
property
Dec. 23, 2015
USD ($)
ft²
Nov. 12, 2015
USD ($)
ft²
Dec. 31, 2016
USD ($)
item
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Real Estate Properties [Line Items]                
Purchase price of property           $ 121,582 $ 94,073 $ 91,813
Multi-Family Properties [Member]                
Real Estate Properties [Line Items]                
Number Of Units | item           5,614    
Red Bank, New Jersey [Member] | Subsequent Event [Member]                
Real Estate Properties [Line Items]                
Number of real estate properties | property     3          
Area of property (in square feet) | ft²     280,000          
Purchase price of property     $ 26,800          
Short Hills And Madison, New Jersey [Member] | Subsequent Event [Member]                
Real Estate Properties [Line Items]                
Number of real estate properties | property   6            
Area of property (in square feet) | ft²   1,100,000            
Purchase price of property   $ 368,000            
Jersey City, New Jersey [Member] | Subsequent Event [Member]                
Real Estate Properties [Line Items]                
Purchase price of property $ 315,000              
Number Of Units | item 523              
Parsippany [Member]                
Real Estate Properties [Line Items]                
Area of property (in square feet) | ft²       147,241        
Purchase price of property       $ 10,300        
Edison [Member]                
Real Estate Properties [Line Items]                
Area of property (in square feet) | ft²         196,128      
Purchase price of property         $ 53,100      
Percentage of leased office property         95.60%