Annual report pursuant to Section 13 and 15(d)

Borrowings - Summary of Borrowings (Detail)

v3.6.0.2
Borrowings - Summary of Borrowings (Detail) - USD ($)
Dec. 31, 2016
Dec. 31, 2015
Debt Instrument [Line Items]    
Deferred financing costs related to mortgage notes and bonds payable   $ 0
Total borrowings, net $ 207,347,012 141,678,935
Mortgage notes and bonds payable, net    
Debt Instrument [Line Items]    
Total borrowings, gross 192,209,029 142,633,157
Deferred financing costs related to mortgage notes and bonds payable (1,412,017) (1,054,222)
Total borrowings, net 190,797,012 141,578,935
Mortgage notes payable | Fixed-rate mortgage notes payable    
Debt Instrument [Line Items]    
Total borrowings, gross $ 142,860,529 107,423,157
Mortgage notes payable | Fixed-rate mortgage notes payable | Minimum    
Debt Instrument [Line Items]    
Interest rate (as percent) 2.90%  
Mortgage notes payable | Fixed-rate mortgage notes payable | Maximum    
Debt Instrument [Line Items]    
Interest rate (as percent) 3.94%  
Mortgage notes payable | Fixed-rate mortgage notes payable | Weighted average    
Debt Instrument [Line Items]    
Interest rate (as percent) 3.25%  
Mortgage notes payable | Variable-rate mortgage notes payable    
Debt Instrument [Line Items]    
Total borrowings, gross $ 0 2,185,000
Bonds payable | Fixed-rate bonds payable    
Debt Instrument [Line Items]    
Total borrowings, gross $ 49,348,500 33,025,000
Bonds payable | Fixed-rate bonds payable | Minimum    
Debt Instrument [Line Items]    
Interest rate (as percent) 2.38%  
Bonds payable | Fixed-rate bonds payable | Maximum    
Debt Instrument [Line Items]    
Interest rate (as percent) 3.29%  
Bonds payable | Fixed-rate bonds payable | Weighted average    
Debt Instrument [Line Items]    
Interest rate (as percent) 2.94%  
Line of credit | Variable-rate revolving lines of credit    
Debt Instrument [Line Items]    
Interest rate (as percent) 3.11%  
Line of credit | Variable-rate revolving lines of credit | Revolving credit facility    
Debt Instrument [Line Items]    
Total borrowings, net $ 16,550,000 $ 100,000