Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Additional Information (Detail)

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Stockholders' Equity - Additional Information (Detail) (USD $)
 0 Months Ended 1 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 06, 2014
Mar. 31, 2011
Jun. 30, 2014
Jun. 30, 2013
Dec. 31, 2013
Dividends Payable [Line Items]            
Common stock, shares issued 17,715,958     17,715,958   15,662,414
Gross proceeds of initial public offering   $ 27,400,000        
Net proceeds of initial public offering   26,000,000        
Maximum aggregate sales price of shares to be issued under open market sale agreement 25,000,000     25,000,000    
Net proceeds under ATM program       7,600,000    
Number of shares sold under open market sale agreement 1,200,000     1,200,000    
Gross proceeds of shares sold under open market sale agreement       21,800,000    
Maximum remaining capacity to sell common stock under open market sale agreement 3,200,000     3,200,000    
Common stock, par value $ 0.001     $ 0.001   $ 0.001
Shares intended to be offered pursuant to primary offering     3,000,000      
Shares intended to be offered pursuant to senior common distribution reinvestment plan     500,000      
Shares of senior common stock sold in ongoing offering 369,553          
Senior common stock ongoing offering, gross proceeds       36,042,000 57,219,000  
Shares of senior common stock issued 441,774     441,774   374,484
Maximum remaining capacity to sell senior common stock 47,000,000     47,000,000    
Public Offering [Member]
            
Dividends Payable [Line Items]            
Common stock, shares issued   1,610,000        
Public offering price per share   $ 17.00        
Senior Common Stock [Member]
            
Dividends Payable [Line Items]            
Common stock, shares issued     3,500,000      
Common stock, par value     $ 0.001      
Common stock shares issued, selling price     $ 15.00      
Senior common stock ongoing offering, gross proceeds $ 5,500,000          
Distribution Reinvestment Plan [Member]
            
Dividends Payable [Line Items]            
Shares of senior common stock issued 15,008     15,008