v3.7.0.1
Equity - Additional Information (Detail) - $ / shares
6 Months Ended
Jun. 30, 2017
Dec. 31, 2016
Equity [Line Items]    
Capital stock, shares authorized 100,000,000  
Common stock, shares authorized 80,000,000 80,000,000
Common stock, par value $ 0.001 $ 0.001
Preferred stock, shares authorized 20,000,000 20,000,000
Preferred stock, par value $ 0.001 $ 0.001
Common stock, voting rights One vote per share  
Preferred stock, shares issued 0 0
Preferred stock, shares outstanding 0 0
Description of total shares quarterly redeemed Total shares redeemed pursuant to the Share Redemption Program in any quarter may not exceed 1% of the total number of shares outstanding at the beginning of the calendar year plus 50% of the total number of any additional shares issued during the prior calendar quarter under the DRIP, provided that the total number of shares redeemed during any calendar year may not exceed 5% of the number of shares outstanding as of the first day of such calendar year.  
Common stock, shares issued 17,290,000 15,158,000
Distribution Reinvestment Plan    
Equity [Line Items]    
Percentage of shares in value offered 98.00%  
Common stock, shares issued 1,317,000 1,076,000
Stock Redeemable After 12 Months but Less than Five Years    
Equity [Line Items]    
Share value redeemable percentage 95.00%  
Stock Redeemable after Five Years    
Equity [Line Items]    
Share value redeemable percentage 100.00%