Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Acquisitions) (Narrative) (Details)

v3.10.0.1
Recent Transactions (Acquisitions) (Narrative) (Details)
$ in Thousands
12 Months Ended
Jan. 25, 2019
USD ($)
item
Jan. 06, 2019
USD ($)
ft²
Dec. 31, 2018
USD ($)
item
Dec. 31, 2017
USD ($)
property
Dec. 31, 2016
USD ($)
Real Estate Properties [Line Items]          
Purchase price of property     $ 168,398 $ 90,068 $ 121,582
Number Of Units | item     1,317    
Multi-Family Properties [Member]          
Real Estate Properties [Line Items]          
Number Of Units | item     6,910    
Jersey City, New Jersey [Member] | Subsequent Event [Member]          
Real Estate Properties [Line Items]          
Purchase price of property $ 264,000        
Number Of Units | item 377        
Iselin, New Jersey [Member] | Subsequent Event [Member]          
Real Estate Properties [Line Items]          
Area of property (in square feet) | ft²   271,988      
Purchase price of property   $ 61,500      
Jersey City, Morris Township And Red Bank, New Jersey [Member]          
Real Estate Properties [Line Items]          
Number of real estate properties | property       3  
Purchase price of property       $ 80,000