Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.8.0.1
Equity - Additional Information (Detail)
 3 Months Ended 6 Months Ended
Apr. 04, 2018
USD ($)
shares
Mar. 27, 2018
USD ($)
$ / shares
shares
Jan. 17, 2018
USD ($)
$ / shares
shares
Jan. 16, 2018
shares
Jan. 10, 2018
USD ($)
$ / shares
shares
Apr. 12, 2017
USD ($)
security
Mar. 31, 2018
USD ($)
$ / shares
shares
Mar. 31, 2017
USD ($)
shares
Sep. 30, 2017
USD ($)
Jan. 09, 2018
shares
Dec. 31, 2017
$ / shares
shares
Aug. 07, 2015
USD ($)
Subsidiary, Sale of Stock [Line Items]                        
Stock authorized and unissued (in shares)         6,500,000              
Common stock, shares authorized (in shares)             91,500,000     98,000,000 98,000,000  
Preferred stock, shares authorized (in shares)             6,500,000       0  
Preferred Stock, Par or Stated Value Per Share | $ / shares             $ 0.001       $ 0  
Common stock, par value (in dollars per share) | $ / shares             $ 0.001       $ 0.001  
Common stock, shares issued (in shares)                     13,791,574  
Price per share of OP units redeemed for cash (in dollars per share) | $ / shares     $ 13.42                  
Maximum number of securities that can be sold (in securities) | security           2            
Proceeds from issuance of equity | $             $ 17,486,000 $ 20,722,000        
Average sales price of common stock sold (in dollars per share) | $ / shares   $ 12.15                    
Discounts and offering expenses | $   $ 12,700,000         $ 685,000 $ 1,054,000        
2017 Registration Statement                        
Subsidiary, Sale of Stock [Line Items]                        
Proceeds from issuance of equity | $                 $ 38,700,000      
Secondary Public Stock Offering                        
Subsidiary, Sale of Stock [Line Items]                        
Sale of common stock sold under sale agreement (in shares)   1,100,000                    
Gross proceeds from issuance of common stock | $   $ 13,400,000                    
ATM Program                        
Subsidiary, Sale of Stock [Line Items]                        
Common stock, shares issued (in shares)             925,561          
Sale of common stock sold under sale agreement (in shares)             316,925          
Common stock, value authorized | $                       $ 30,000,000.0
Average sales price price (in dollars per share) | $ / shares             $ 12.83          
Common stock, value, outstanding | $             $ 11,900,000          
Common stock, value, issued | $             $ 11,700,000          
At Market Program 2017 Issuances                        
Subsidiary, Sale of Stock [Line Items]                        
Average sales price price (in dollars per share) | $ / shares             $ 13.00          
Common stock, value, outstanding | $             $ 4,100,000          
Common Stock | 2017 Registration Statement                        
Subsidiary, Sale of Stock [Line Items]                        
Securities allowed for issuance (amount up to) | $           $ 300,000,000            
Preferred Stock | 2017 Registration Statement                        
Subsidiary, Sale of Stock [Line Items]                        
Common stock, shares issued (in shares)             3,111,000          
Common stock issued (in shares)             254,575          
Limited Partner                        
Subsidiary, Sale of Stock [Line Items]                        
OP units redeemed for common stock (in shares)     7,700                  
Gladstone Land Limited Partnership                        
Subsidiary, Sale of Stock [Line Items]                        
Company's ownership percent (as percent)             94.00%       93.20%  
OP units held by non-controlling limited partners (in shares)             970,605 1,008,105        
OP units held by non-controlling interest limited partners (in shares)             970,605          
Gladstone Land Limited Partnership | Limited Partner                        
Subsidiary, Sale of Stock [Line Items]                        
OP units redeemed (in shares)       37,500                
Common stock issued (in shares)     7,700                  
OP units redeemed for cash (in shares)     29,800                  
OP units redeemed for cash | $     $ 400,000                  
Series B Preferred Stock                        
Subsidiary, Sale of Stock [Line Items]                        
Common stock, shares issued (in shares)             15,216,199          
Series B Preferred Stock | Preferred Stock                        
Subsidiary, Sale of Stock [Line Items]                        
Securities allowed for issuance (amount up to) | $         $ 150,000,000              
Average sales price of common stock sold (in dollars per share) | $ / shares         $ 25              
Discounts and offering expenses | $             $ 279,000          
Maximum amount authorized in Primary Offering (in shares)         6,000,000              
Dividend rate (as percent)         6.00%              
Proceeds from Issuance of Preferred Stock and Preference Stock | $         $ 131,300,000              
Series B Preferred Stock | Preferred Stock | Over-allotment option                        
Subsidiary, Sale of Stock [Line Items]                        
Stock offered pursuant to DRIP (in shares)         500,000              
OP Unit Holder                        
Subsidiary, Sale of Stock [Line Items]                        
Minimum period required to exercise, in months             12 months          
Subsequent event | Over-allotment option                        
Subsidiary, Sale of Stock [Line Items]                        
Sale of common stock sold under sale agreement (in shares) 165,000                      
Gross proceeds from issuance of common stock | $ $ 2,000,000                      
Discounts and offering expenses | $ $ 1,900,000