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Debt - Additional Information (Detail) - USD ($)
3 Months Ended
May 10, 2018
Feb. 12, 2018
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Debt Instrument [Line Items]          
Mortgage loan outstanding balance     $ 357,200,000   $ 297,300,000
Payments on mortgage loans     $ 1,649,012 $ 3,566,914  
7.25% Unsecured Notes [Member]          
Debt Instrument [Line Items]          
Interest rate on loan   7.25%      
Borrowed amount   $ 25,000,000      
Debt instrument maturity date     Feb. 15, 2021    
Debt instrument callable date     Feb. 15, 2019    
Notes face value   101.00%      
Subsequent Event [Member]          
Debt Instrument [Line Items]          
Payments on mortgage loans $ 4,000,000