Quarterly report pursuant to Section 13 or 15(d)

Borrowings - Additional Information (Detail)

v3.8.0.1
Borrowings - Additional Information (Detail)
3 Months Ended 9 Months Ended
Sep. 19, 2017
USD ($)
Sep. 30, 2017
USD ($)
debt_instrument
Sep. 30, 2016
Sep. 30, 2017
USD ($)
debt_instrument
Sep. 30, 2016
May 31, 2017
USD ($)
debt_instrument
Jan. 12, 2017
USD ($)
Dec. 31, 2016
USD ($)
Oct. 05, 2016
USD ($)
Oct. 04, 2016
USD ($)
Jun. 16, 2016
USD ($)
Dec. 05, 2014
USD ($)
May 09, 2014
USD ($)
Debt Instrument [Line Items]                          
Weighted average interest rate (as percent)   3.44% 3.29% 3.33% 3.27%                
Borrowings under lines of credit   $ 5,100,000   $ 5,100,000       $ 16,550,000          
Metlife Term Loans                          
Debt Instrument [Line Items]                          
Proceeds from notes payable $ 27,500,000                        
Metlife Term Loans | Notes and bonds payables                          
Debt Instrument [Line Items]                          
Face amount of debt           $ 15,300,000              
Stated interest rate (as percent) 3.85%                        
Number of debt instruments | debt_instrument           2              
Farm Credit Notes Payable                          
Debt Instrument [Line Items]                          
Reduced stated interest rate (as percent)       17.20%                  
Reduction in basis points (as percent)       0.61%                  
Number of debt instruments | debt_instrument   14   14                  
MetLife Facility                          
Debt Instrument [Line Items]                          
Maximum borrowing capacity                 $ 200,000,000 $ 125,000,000      
2015 Metlife Term Note (MetLife)                          
Debt Instrument [Line Items]                          
Face amount of debt                         $ 100,000,000
2015 Metlife Line of Credit (MetLife)                          
Debt Instrument [Line Items]                          
Face amount of debt                         $ 25,000,000
2016 Metlife Term Note (MetLife)                          
Debt Instrument [Line Items]                          
Line of credit, carrying value                 50,000,000        
2016 Metlife Line of Credit (MetLife)                          
Debt Instrument [Line Items]                          
Line of credit, carrying value                 $ 25,000,000        
Farmer Mac Bonds Payable                          
Debt Instrument [Line Items]                          
Face amount of debt   $ 125,000,000   $ 125,000,000             $ 125,000,000 $ 75,000,000  
Number of debt instruments | debt_instrument   14   14                  
Extension period of debt       2 years                  
Farmer Mac Bonds Payable, 2017 Issuances                          
Debt Instrument [Line Items]                          
Face amount of debt             $ 35,625,000            
Number of debt instruments | debt_instrument   5   5                  
Mortgage notes and bonds payable | Notes and bonds payables                          
Debt Instrument [Line Items]                          
Aggregate fair value of mortgage notes payable outstanding   $ 286,300,000   $ 286,300,000                  
Mortgage notes payable, carrying value   292,100,000   292,100,000                  
Short-term variable-rate mortgage notes and bonds payable | Notes and bonds payables                          
Debt Instrument [Line Items]                          
Borrowings under lines of credit   $ 5,100,000   $ 5,100,000