Annual report pursuant to Section 13 and 15(d)

Subsequent Events (Details)

v3.6.0.2
Subsequent Events (Details)
 12 Months Ended
Feb. 01, 2017
USD ($)
property
Jan. 31, 2017
USD ($)
property
mortgage
Dec. 31, 2016
USD ($)
property
mortgage
shares
Dec. 31, 2015
USD ($)
shares
Dec. 31, 2014
USD ($)
Jan. 11, 2017
shares
Subsequent Event [Line Items]            
Gain on sale of real estate, net     $ 242,000 $ 1,538,000 $ 1,240,000  
Number of mortgages repaid | mortgage     7      
Number of properties collateralized | mortgage     16      
Principal repayments on mortgage notes payable     $ 88,899,000 $ 66,714,000 $ 8,144,000  
Number of properties collateralized in mortgage notes payable | property     94      
Variable Rate Mortgage Loans [Member]            
Subsequent Event [Line Items]            
Number of properties collateralized in mortgage notes payable | property     18      
Fixed Rate Mortgage Loans [Member]            
Subsequent Event [Line Items]            
Number of properties collateralized in mortgage notes payable | property     52      
Mandatorily Redeemable Preferred Stock [Member] | Series C Preferred Stock [Member]            
Subsequent Event [Line Items]            
Preferred stock, shares authorized (in shares) | shares     160,000 1,700,000    
Subsequent Event [Member]            
Subsequent Event [Line Items]            
Partnership interest, shares authorized (in shares) | shares           0
Subsequent Event [Member] | Variable Rate Mortgage Loans [Member]            
Subsequent Event [Line Items]            
Mortgage balance   $ 10,000,000        
Number of properties collateralized in mortgage notes payable | property   3        
Subsequent Event [Member] | Fixed Rate Mortgage Loans [Member]            
Subsequent Event [Line Items]            
Number of properties collateralized | property 3          
Principal repayments on mortgage notes payable $ 13,800,000          
Debt instrument stated percentage (as percent) 6.00%          
Subsequent Event [Member] | Franklin, New Jersey [Member]            
Subsequent Event [Line Items]            
Property sold   $ 12,800,000        
Gain on sale of real estate, net   $ 5,900,000.0        
Subsequent Event [Member] | Franklin, New Jersey [Member] | Variable Rate Mortgage Loans [Member]            
Subsequent Event [Line Items]            
Number of mortgages repaid | mortgage   1        
Number of properties collateralized | mortgage   4        
Principal repayments on mortgage notes payable   $ 8,200,000        
Subsequent Event [Member] | Mandatorily Redeemable Preferred Stock [Member] | Series C Preferred Stock [Member]            
Subsequent Event [Line Items]            
Preferred stock, shares authorized (in shares) | shares           0