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Summary of Significant Accounting Policies - Schedule of Recurring Assets and Liabilities Measured at Fair Value (Detail) - USD ($)
Mar. 31, 2018
Dec. 31, 2017
Level 1 [Member] | Unsecured Notes [Member]    
Derivatives Fair Value [Line Items]    
Debt instruments measured at fair value $ (26,000,000)  
Level 2 [Member] | Interest Rate Cap [Member]    
Derivatives Fair Value [Line Items]    
Interest rate cap 17,942 $ 5,213
Level 2 [Member] | Mortgage Loans [Member]    
Derivatives Fair Value [Line Items]    
Debt instruments measured at fair value $ (352,396,367) $ (292,368,370)