Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events - Additional Information (Details)

v3.10.0.1
Subsequent Events - Additional Information (Details)
 1 Months Ended 3 Months Ended 9 Months Ended
Nov. 01, 2018
USD ($)
a
option
Nov. 08, 2018
USD ($)
shares
Oct. 31, 2018
USD ($)
Sep. 30, 2018
USD ($)
a
Sep. 30, 2017
USD ($)
a
Sep. 30, 2018
USD ($)
a
Sep. 30, 2017
USD ($)
a
Oct. 09, 2018
$ / shares
Subsequent Event [Line Items]                
Area of real estate property (in acres) | a       67,826 61,794 67,826 61,794  
Rental revenue       $ 8,013,000 $ 6,561,000 $ 21,333,000 $ 18,302,000  
Financing fee       57,000 28,000 59,000 30,000  
Base management fee       690,000 $ 523,000 2,102,000 $ 1,446,000  
Subsequent event | Farm Credit West Note Payable due 2043                
Subsequent Event [Line Items]                
Proceeds from notes payable $ 13,800,000              
Interest rate (as percent) 5.61%              
Series B Preferred Stock | Subsequent event                
Subsequent Event [Line Items]                
Sale of stock sold under sale agreement (in shares) | shares   199,353            
Proceeds from issuance of preferred stock   $ 5,000,000            
Net proceeds from issuance of stock   4,500,000            
Distributions per share | $ / shares               $ 0.375
Common Stock | Subsequent event                
Subsequent Event [Line Items]                
Distributions per share | $ / shares               $ 0.1332
Gladstone Securities                
Subsequent Event [Line Items]                
Payment of management fees       843,000   890,000    
Debt Financing Costs | Gladstone Securities | Subsequent event | Farm Credit West Note Payable due 2043                
Subsequent Event [Line Items]                
Financing fee $ 17,000              
Sales Commissions and Broker-Dealer Fees | Gladstone Securities | Series B Preferred Stock | Subsequent event                
Subsequent Event [Line Items]                
Payment of management fees   459,000            
Sales Commissions and Broker-Dealer Fees | Gladstone Securities | Series B Preferred Stock | Subsequent event                
Subsequent Event [Line Items]                
Base management fee   $ 484,000            
Sunnyside Avenue, 951-acre farm in Madera County, California | Subsequent event                
Subsequent Event [Line Items]                
Area of real estate property (in acres) | a 951              
Purchase price $ 23,000,000              
Lease term (in years) 8 years              
Number of renewal options | option 2              
Renewal term 5 years              
Annualized straight-line rent $ 1,200,000              
119-acre farm in Van Buren County, Michigan                
Subsequent Event [Line Items]                
Rental revenue       28,000   85,000    
Accretion of tenant-funded improvements       $ 7,000   $ 20,000    
61-acre farm in Hillsborough County, Florida | Subsequent event                
Subsequent Event [Line Items]                
Annualized straight-line rent     $ 15,000          
Annualized straight-line rent, increase (decrease)     $ 56,000          
Annualized straight-line rent, increase (decrease), percentage     78.80%