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Stockholder Equity and Noncontrolling Interest - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
Sep. 11, 2017
Jan. 31, 2018
Jun. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Aug. 04, 2017
Class Of Stock [Line Items]              
At-the-market sales agreement, common stock par value per share             $ 0.01
At-the-market agreement to sell common shares, maximum offer price             $ 150,000,000
At-the-market agreement to sell common shares, compensation to sales agents             2.00%
At-the-market sales agreement, obligation to sell common shares             $ 0
OP Units issued     166,604        
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable     $ 1,654,000        
Limited partnership interest received in exchange for issuance of common stock       64,202 245,982    
OP Units outstanding       3,011,351      
OP Units redemption value       $ 30,385,000      
Share price       $ 10.09   $ 7.51  
Subsequent Event              
Class Of Stock [Line Items]              
Limited partnership interest received in exchange for issuance of common stock   186,717          
Common Shares              
Class Of Stock [Line Items]              
Common stock issued       15,539,900 28,750,000 15,105,669  
Exchange of units to common stock       64,202 245,980 52,933  
Common Shares | Subsequent Event              
Class Of Stock [Line Items]              
Exchange of units to common stock   186,717          
ATM Sales Agreement              
Class Of Stock [Line Items]              
Shares issued       1,164,900      
Average price per share       $ 10.38      
Net proceeds after deducting commissions       $ 11,851,000      
Commissions       $ 242,000      
Underwritten public offering              
Class Of Stock [Line Items]              
Common stock issued 12,500,000            
Common stock, par value $ 9.25            
Public offering price per share $ 1,875,000            
Net proceeds of public offering $ 126,100,000